Home » Public Forums » GMCnet » Bigger Tires
| Bigger Tires [message #107145] |
Tue, 30 November 2010 13:01  |
Jerry Hartley
Messages: 17
Registered: May 2004
Karma: 0
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Junior Member |
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I just put new tires on my GMC Birchaven. Replaced 225 75R16 with Michelin LTX MS2 235 85 R16. Clearance is definitely an issue. Pictures have been posted on the GMC photo website. The following link should get you there. http://www.gmcmhphotos.com "Bigger Tires" (Someone let me know how to best point to this location). I solved this problem by completing installation of the Quadrabag system. Obviously this would not be a feasible solution if it were the only reason.
I wanted the bigger tires because my Cadillac 500 CID (3.70 final drive) runs 2600 rpm at 60 mph. I don't like the engine noise or the mileage (8.3 mpg). Anyway, it has too much horsepower and too much torque. Yeah, right.
I have read the discussions about tire sizes. How have other people installed these bigger tires? I could not have left the bigger tires on with the original airbags.
Jerry Hartley
Sequim, WA
1977 Birchaven CAD 500/3.70 Final
1976 Royal
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| Re: [GMCnet] Bigger Tires [message #107149 is a reply to message #107145] |
Tue, 30 November 2010 13:19  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Jerry, you would probably be happier with 3:50 Diff gearing with all that
torque & horsepower that the Cad 500 gives you and may even pick up a mile
or two per gallon. Ask around, someone with a 403 might want to trade for
your 3:70. The 403s are an oversquare engine and are happier with a few more
rpms. Good fit for both.
Jim Hupy
Salem, Or
78 Royale 403
On Tue, Nov 30, 2010 at 11:01 AM, Jerry Hartley <jhartley@wavecable.com>wrote:
>
>
> I just put new tires on my GMC Birchaven. Replaced 225 75R16 with Michelin
> LTX MS2 235 85 R16. Clearance is definitely an issue. Pictures have been
> posted on the GMC photo website. The following link should get you there.
> http://www.gmcmhphotos.com "Bigger Tires" (Someone let me know how to best
> point to this location). I solved this problem by completing installation of
> the Quadrabag system. Obviously this would not be a feasible solution if it
> were the only reason.
>
> I wanted the bigger tires because my Cadillac 500 CID (3.70 final drive)
> runs 2600 rpm at 60 mph. I don't like the engine noise or the mileage (8.3
> mpg). Anyway, it has too much horsepower and too much torque. Yeah, right.
>
> I have read the discussions about tire sizes. How have other people
> installed these bigger tires? I could not have left the bigger tires on with
> the original airbags.
>
> Jerry Hartley
> Sequim, WA
> 1977 Birchaven CAD 500/3.70 Final
> 1976 Royal
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Bigger Tires [message #107164 is a reply to message #107145] |
Tue, 30 November 2010 18:15 |
Terrance Boyd
Messages: 38
Registered: October 2008
Karma: 0
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Member |
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I read the GMCMI news letter tha t told me the Goodyear G159 235 85/16 was
probably the correct tire for the GMC, because it is 1" smaller in diameter
than other brands.So I ordered six, when they came I had them mounted,they
were close to the airbag cone (1/2").
I didn't have any problems with them, but I did notice a drop in
performance. I sat down with paper and pencil (old fashion calculator) and
figured I had loss about 5%. That's when I put in the 321 and regained the
5%, it also put the speedometer right. Trying to keep the speedometer fairly
close I'm now running with 245 75/16. Just rambling.
Terry
On Tue, Nov 30, 2010 at 12:01 PM, Jerry Hartley <jhartley@wavecable.com>wrote:
>
>
> I just put new tires on my GMC Birchaven. Replaced 225 75R16 with Michelin
> LTX MS2 235 85 R16. Clearance is definitely an issue. Pictures have been
> posted on the GMC photo website. The following link should get you there.
> http://www.gmcmhphotos.com "Bigger Tires" (Someone let me know how to best
> point to this location). I solved this problem by completing installation of
> the Quadrabag system. Obviously this would not be a feasible solution if it
> were the only reason.
>
> I wanted the bigger tires because my Cadillac 500 CID (3.70 final drive)
> runs 2600 rpm at 60 mph. I don't like the engine noise or the mileage (8.3
> mpg). Anyway, it has too much horsepower and too much torque. Yeah, right.
>
> I have read the discussions about tire sizes. How have other people
> installed these bigger tires? I could not have left the bigger tires on with
> the original airbags.
>
> Jerry Hartley
> Sequim, WA
> 1977 Birchaven CAD 500/3.70 Final
> 1976 Royal
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Bigger Tires [message #107165 is a reply to message #107164] |
Tue, 30 November 2010 18:21 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Terry,
Here is a real good chart on tire size verses final drive ratios.
http://www.gmceast.com/technical/Brown_Drive_Tire_Ratios.pdf
JR Wright
On Nov 30, 2010, at 7:15 PM, Terrance Boyd wrote:
> I read the GMCMI news letter tha t told me the Goodyear G159 235
> 85/16 was
> probably the correct tire for the GMC, because it is 1" smaller in
> diameter
> than other brands.So I ordered six, when they came I had them
> mounted,they
> were close to the airbag cone (1/2").
> I didn't have any problems with them, but I did notice a drop in
> performance. I sat down with paper and pencil (old fashion
> calculator) and
> figured I had loss about 5%. That's when I put in the 321 and
> regained the
> 5%, it also put the speedometer right. Trying to keep the
> speedometer fairly
> close I'm now running with 245 75/16. Just rambling.
> Terry
>
> On Tue, Nov 30, 2010 at 12:01 PM, Jerry Hartley <jhartley@wavecable.com
> >wrote:
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Bigger Tires [message #107167 is a reply to message #107165] |
Tue, 30 November 2010 18:27 |
Terrance Boyd
Messages: 38
Registered: October 2008
Karma: 0
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Member |
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Thank You John
On Tue, Nov 30, 2010 at 5:21 PM, John Wright <powerjon@chartermi.net> wrote:
> Terry,
> Here is a real good chart on tire size verses final drive ratios.
>
> http://www.gmceast.com/technical/Brown_Drive_Tire_Ratios.pdf
>
> JR Wright
>
> On Nov 30, 2010, at 7:15 PM, Terrance Boyd wrote:
>
> > I read the GMCMI news letter tha t told me the Goodyear G159 235
> > 85/16 was
> > probably the correct tire for the GMC, because it is 1" smaller in
> > diameter
> > than other brands.So I ordered six, when they came I had them
> > mounted,they
> > were close to the airbag cone (1/2").
> > I didn't have any problems with them, but I did notice a drop in
> > performance. I sat down with paper and pencil (old fashion
> > calculator) and
> > figured I had loss about 5%. That's when I put in the 321 and
> > regained the
> > 5%, it also put the speedometer right. Trying to keep the
> > speedometer fairly
> > close I'm now running with 245 75/16. Just rambling.
> > Terry
> >
> > On Tue, Nov 30, 2010 at 12:01 PM, Jerry Hartley <jhartley@wavecable.com
> > >wrote:
>
> _______________________________________________
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> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Bigger Tires [message #107188 is a reply to message #107145] |
Tue, 30 November 2010 21:46 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Those of you that think that 3.55 will get you better mileage are wrong.
Having sold over 3,000 of them has shown me that you gain power in the
torque range and the load on the engine decreases so the carburetor
runs leaner and the distributor vacuum increases and the timing
advances and improves mileage.
Lot of you drive on the average 50-60 mph. So the rpm is not always in
the torque range where you will benefit.
Other than a brand new engine that is fully computerised from a 2000
year vehicle, you need to get into the 2500 plus rpm to benefit.
I drive hard and travel 65-75mph. I can use any gear I want , but
after try ing everything from 3.21, 3.41, 3.55,3.70, I find that the
3.70 gives me the mileage and performance.
I have a CAD 540 bored and stroked, port injected and twin turbo ed
engine and pull 7.5-8 mpg pulling Graces Oldsmobile van which scales
in at over 6,000 lbs.
When I'm not towing I will get 8-10 as I drive 70-80mph.
It takes tremendous power to push against the wind.
Don't tell me you have so much torque that you need to gear up to a
higher ratio.
If your engine makes noise, your engine compartment needs to be gasket properly.
If your mileage suffers,check the mechanical advance and the vac
module along with the carb.
80% of the people that went to the 3.70 will tell me that the mileage
did not change and the power went up.
I have a friends that run our 4.10 gears at 55mph and tell me they get 12mpg.
Before that they ran a 3.55 and were getting 8mpg.
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Bigger Tires [message #107197 is a reply to message #107145] |
Tue, 30 November 2010 21:52 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Jerrry,
There is something wrong withyour ignition system if thatis all you
can get out of your Cad.
I can work out a sweet deal if you want to try a 3,55.
Call me. (800)752-7502
On Tue, Nov 30, 2010 at 11:01 AM, Jerry Hartley <jhartley@wavecable.com> wrote:
>
>
> I just put new tires on my GMC Birchaven. Replaced 225 75R16 with Michelin LTX MS2 235 85 R16. Clearance is definitely an issue. Pictures have been posted on the GMC photo website. The following link should get you there. http://www.gmcmhphotos.com "Bigger Tires" (Someone let me know how to best point to this location). I solved this problem by completing installation of the Quadrabag system. Obviously this would not be a feasible solution if it were the only reason.
>
> I wanted the bigger tires because my Cadillac 500 CID (3.70 final drive) runs 2600 rpm at 60 mph. I don't like the engine noise or the mileage (8.3 mpg). Anyway, it has too much horsepower and too much torque. Yeah, right.
>
> I have read the discussions about tire sizes. How have other people installed these bigger tires? I could not have left the bigger tires on with the original airbags.
>
> Jerry Hartley
> Sequim, WA
> 1977 Birchaven CAD 500/3.70 Final
> 1976 Royal
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Bigger Tires [message #107242 is a reply to message #107164] |
Wed, 01 December 2010 12:23 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Nov 30, 2010, at 5:15 PM, Terrance Boyd wrote:
> I read the GMCMI news letter tha t told me the Goodyear G159 235 85/16 was
> probably the correct tire for the GMC, because it is 1" smaller in diameter
> than other brands.So I ordered six, when they came I had them mounted,they
> were close to the airbag cone (1/2").
> I didn't have any problems with them, but I did notice a drop in
> performance. I sat down with paper and pencil (old fashion calculator) and
> figured I had loss about 5%. That's when I put in the 321 and regained the
> 5%, it also put the speedometer right. Trying to keep the speedometer fairly
> close I'm now running with 245 75/16. Just rambling.
> Terry
>
That information was from an old GMCMI newsletter #35 dated back to 1991.
A careful read of that information would show that the member said it was only for a Goodyear Unisteel tire which I do not believe is still made in that size..
The article goes on to say that "almost all brand names of the LT235/85R15 are at least 1" larger than the 9.50 tires which makes them unsuitable for the GMC".
Tires have changed a lot in the last 19 years since the information was submitted by a member.
Especially with tires one should not go by information that old.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Bigger Tires [message #107289 is a reply to message #107242] |
Wed, 01 December 2010 21:30 |
Terrance Boyd
Messages: 38
Registered: October 2008
Karma: 0
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Member |
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The Goodyear G159 WAS a unisteel tire.Yes, it is no longer made in the 235
85/16 size. But when I put them on in1993 they were.
Terry
On Wed, Dec 1, 2010 at 11:23 AM, Emery Stora <emerystora@mac.com> wrote:
>
> On Nov 30, 2010, at 5:15 PM, Terrance Boyd wrote:
>
> > I read the GMCMI news letter tha t told me the Goodyear G159 235 85/16
> was
> > probably the correct tire for the GMC, because it is 1" smaller in
> diameter
> > than other brands.So I ordered six, when they came I had them
> mounted,they
> > were close to the airbag cone (1/2").
> > I didn't have any problems with them, but I did notice a drop in
> > performance. I sat down with paper and pencil (old fashion calculator)
> and
> > figured I had loss about 5%. That's when I put in the 321 and regained
> the
> > 5%, it also put the speedometer right. Trying to keep the speedometer
> fairly
> > close I'm now running with 245 75/16. Just rambling.
> > Terry
> >
> That information was from an old GMCMI newsletter #35 dated back to 1991.
> A careful read of that information would show that the member said it was
> only for a Goodyear Unisteel tire which I do not believe is still made in
> that size..
> The article goes on to say that "almost all brand names of the LT235/85R15
> are at least 1" larger than the 9.50 tires which makes them unsuitable for
> the GMC".
>
> Tires have changed a lot in the last 19 years since the information was
> submitted by a member.
> Especially with tires one should not go by information that old.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Bigger Tires [message #107292 is a reply to message #107289] |
Wed, 01 December 2010 23:28 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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I had thought from your emai that you had just bought them. I guess
that you can stop worrying about the size now since it's 17 years
since you bought them.
I assume that you are no longer using them. -- I HOPE!
Emery Stora
On Dec 1, 2010, at 8:30 PM, Terrance Boyd <newtent@gmail.com> wrote:
> The Goodyear G159 WAS a unisteel tire.Yes, it is no longer made in
> the 235
> 85/16 size. But when I put them on in1993 they were.
> Terry
>
> On Wed, Dec 1, 2010 at 11:23 AM, Emery Stora <emerystora@mac.com>
> wrote:
>
>>
>> On Nov 30, 2010, at 5:15 PM, Terrance Boyd wrote:
>>
>>> I read the GMCMI news letter tha t told me the Goodyear G159 235 85/16
>> was
>>> probably the correct tire for the GMC, because it is 1" smaller in
>> diameter
>>> than other brands.So I ordered six, when they came I had them
>> mounted,they
>>> were close to the airbag cone (1/2").
>>> I didn't have any problems with them, but I did notice a drop in
>>> performance. I sat down with paper and pencil (old fashion
>>> calculator)
>> and
>>> figured I had loss about 5%. That's when I put in the 321 and
>>> regained
>> the
>>> 5%, it also put the speedometer right. Trying to keep the
>>> speedometer
>> fairly
>>> close I'm now running with 245 75/16. Just rambling.
>>> Terry
>>>
>> That information was from an old GMCMI newsletter #35 dated back
>> to 1991.
>> A careful read of that information would show that the member said
>> it was
>> only for a Goodyear Unisteel tire which I do not believe is still
>> made in
>> that size..
>> The article goes on to say that "almost all brand names of the
>> LT235/85R15
>> are at least 1" larger than the 9.50 tires which makes them
>> unsuitable for
>> the GMC".
>>
>> Tires have changed a lot in the last 19 years since the information
>> was
>> submitted by a member.
>> Especially with tires one should not go by information that old.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: Bigger Tires [message #107298 is a reply to message #107145] |
Thu, 02 December 2010 06:53 |
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Hardie Johnson
Messages: 483
Registered: January 2004
Location: Raleigh NC
Karma: 0
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Senior Member |
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| AnnabelleR wrote on Thu, 02 December 2010 06:25 |
I have a question regarding bigger tires <> What's the difference if cars have bigger tires? For example, I notice sports cars usually have 17- or 18-inch tires. "Ordinary" cars usually have 15-inch tires. Upper trim levels of these cars get bigger tires. I heard bigger tires enable a car to go a further distance in a same amount of time, because of the bigger circumferences. Bigger tires can stop a car better because of wider surface contact. But bigger tires need more gas, possibly more road noise. What are all the pros and cons of bigger versus "normal"-size tires?
|
The cars you see with large diameter _wheels_ have low profile ratio _tires_ and the rolling diameter nets out about the same. While this makes for a cool look, it is inefficient because heavy metal wheel has replaced lighter rubber. Most cars today have 16" wheels, higher performance cars have larger diameter wheels.
Bigger tires don't, "enable a car to go a further distance in a same amount of time", pushing on the accelerator does that - you go faster. Bigger tires allow the engine to rotate slower at a given speed.
With our coaches the problem is it is not easy to find tires for the original 16.5" wheels so many have switched to a more standard 16.0" wheel. Also, the first batch of GMC wheels were not suitable for modern radial tires.
This change of tire (not the wheel) has an effect on the rolling radius and will throw off the calibration of the speedometer.
The stock 3.07 final drive ratio is low and luggs the engine, so one way to deal with this is to go with a 16.0" tire with a low profile. This will give a harsher ride. I am not sure why someone would put on a larger tire as this makes to lugging worse. Maybe it is related to load capacity, which is a BIG concern for our coaches ??
The solution is to go with a tire that is the same outside diameter as original, and install a higher numerical ratio final drive.
The fuel economy does not suffer because, over a range of rpm, the engine delivers, more or less, the same power and consumes the same fuel at a given highway speed. A higher numerical ratio allows the engine to operate more efficiently, especially on acceleration, and fuel economy may improve.
As for the speedo, check and calibrate and adjust the gearing, or rely on your GPS.
"Not 'all' the pros and cons of bigger tires."
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC
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| Re: [GMCnet] Bigger Tires [message #107302 is a reply to message #107145] |
Thu, 02 December 2010 08:08 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Ali,
I would suggest you visit your local tire shop and ask them these questions
or try Google.
Good luck,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Annabelle
Sent: Thursday, December 02, 2010 5:26 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Bigger Tires
Hello,
I have a question regarding bigger tires and i hope you will let me know
about it.The question is What's the difference if cars have bigger tires?
For example, I notice sports cars usually have 17- or 18-inch tires.
"Ordinary" cars usually have 15-inch tires. Upper trim levels of these cars
get bigger tires. I heard bigger tires enable a car to go a further distance
in a same amount of time, because of the bigger circumferences. Bigger tires
can stop a car better because of wider surface contact. But bigger tires
need more gas, possibly more road noise. What are all the pros and cons of
bigger versus "normal"-size tires?
Thanks in advance.
Ali
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Bigger Tires [message #107306 is a reply to message #107302] |
Thu, 02 December 2010 08:20 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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As someone else has stated, the "premium" wheels
on higher-end autos (and trucks) wear much lower
profile tires to basically keep close to the same
running diameter (and engine RPM). These lower
profile tires have considerably lower (and stiffer)
sidewalls which will normally improve handling and
steering response.
All things being equal, the ride comfort will suffer
and with the greater tread width, will hydroplane
more easily with water on the road surface.
I believe "standard" auto tires these days wear a
75% to 78% profile ratio. "Performance" tires are
now available with as low as 25 or 30 percent for
the maximum possible grip in turns.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
----------------------------------------
> From: robmueller@iinet.net.au
> To: gmclist@temp.gmcnet.org
> Date: Thu, 2 Dec 2010 08:08:19 -0600
> Subject: Re: [GMCnet] Bigger Tires
>
> Ali,
>
> I would suggest you visit your local tire shop and ask them these questions
> or try Google.
>
> Good luck,
> Rob M.
> USAussie
>
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Annabelle
> Sent: Thursday, December 02, 2010 5:26 AM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Bigger Tires
>
>
> Hello,
> I have a question regarding bigger tires and i hope you will let me know
> about it.The question is What's the difference if cars have bigger tires?
> For example, I notice sports cars usually have 17- or 18-inch tires.
> "Ordinary" cars usually have 15-inch tires. Upper trim levels of these cars
> get bigger tires. I heard bigger tires enable a car to go a further distance
> in a same amount of time, because of the bigger circumferences. Bigger tires
> can stop a car better because of wider surface contact. But bigger tires
> need more gas, possibly more road noise. What are all the pros and cons of
> bigger versus "normal"-size tires?
> Thanks in advance.
> Ali
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| Re: [GMCnet] Bigger Tires [message #107308 is a reply to message #107145] |
Thu, 02 December 2010 08:29 |
GMC_LES
Messages: 569
Registered: October 2009
Location: Montreal
Karma: 0
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Senior Member |
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I get the impression that the main reason people are interested in going to a
larger tire is due to availability and commonality.
The larger 235/85-16 is a very common tire on today's 3/4 & 1 ton trucks. You
can find lots of them just about anywhere tires are sold. The correct size
225/75-16 is less common, but still easily found in most tire stores today.
Going to a tire with a higher aspect ratio(the 2nd number in the size) MAY
affect ride quality, handling, & vehicle stability, either positively or
negatively due to the taller sidewall. It all depends on the quality & specs of
the tire you choose as well as the inflation pressures you choose to run. Larger
tires also typically have a higher weight carrying capacity. The tendancy might
be to run lower pressures with the larger tires, but that can have a negative
affect on vehicle stability.
Choose your tire brand and size carefully. Straying away from what is known to
work well is putting your travelling fun in jeopardy.
Thanks,
Les Burt
________________________________
From: Annabelle <wholost@live.com>
To: gmclist@temp.gmcnet.org
Sent: Thu, December 2, 2010 6:25:34 AM
Subject: Re: [GMCnet] Bigger Tires
Hello,
I have a question regarding bigger tires and i hope you will let me know about
it.The question is What's the difference if cars have bigger tires? For example,
I notice sports cars usually have 17- or 18-inch tires. "Ordinary" cars usually
have 15-inch tires. Upper trim levels of these cars get bigger tires. I heard
bigger tires enable a car to go a further distance in a same amount of time,
because of the bigger circumferences. Bigger tires can stop a car better because
of wider surface contact. But bigger tires need more gas, possibly more road
noise. What are all the pros and cons of bigger versus "normal"-size tires?
Thanks in advance.
Ali
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Les Burt
Montreal
1975 Eleganza 26ft
A work in Progress
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| Re: [GMCnet] Bigger Tires [message #107381 is a reply to message #107308] |
Fri, 03 December 2010 09:40 |
stick miller
Messages: 1036
Registered: March 2010
Location: Americus, Georgia
Karma: 0
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Senior Member |
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Oversize tires have so far cost me an airbag and 2 T-Skirts. The airbag was my fault as a newbie. I did not level the coach properly and took a turn with a dip I shouldn't have attempetd. The tire rubbed a hole in a perfectly good airbag. That alone could have been prevented with proper leveling and a more knowledgable owner and a different route.
The T-Skirts are a different issue. When the coach is lowered in the rear for any reason the tires rest on or very near the T-skirts unless watched carefully. Clearance is very tight at ride height and as a result the T-skirts are ragged along points of contact. I'm not letting them touch any more, but I'm also not able to lower as much as I'd like for draining the fresh water.
I will go with original size tires in future purchases.
By the way, my father's company (he was the President) bought a GMC motorhome new, probably in '74 or '75. When it came in my mother refused to accept it because it didn't have white sidewall tires and no "respectable woman is going to ride in a vehicle with blackwalls."
It's funny how tastes change. I have trouble finding any brand of whitewalls for my '96 Cadillac Fleetwood. I have 3 year old Khumos now and I'm not sure what I'll do when the time comes to replace them. All I know is that that car sure doesn't look right without them.
Stick Miller
'78 Royale - "White Trash" - she left me for another man
'76 Eleganza - "Cousin Eddie" Sold
'84 Bluebird Wanderlodge - "Past Tents"
Americus, GA
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| Re: [GMCnet] Bigger Tires [message #107390 is a reply to message #107381] |
Fri, 03 December 2010 11:05 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
Karma: 0
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Senior Member |
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Stick, white walls are easy to find for older, "vintage" cars.
Wallace Wade in Dallas 214-688-0091 carries many sizes. Cooper and others still make them. He also carries Red Lines for muscle cars. A google search might find you a source in Atlanta, or call Wallace maybe he will.
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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| Re: Bigger Tires [message #107392 is a reply to message #107145] |
Fri, 03 December 2010 11:09 |
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I think the only way to avoid clearance issues in the rear with larger tires is to go with the 4 bager system, since it raises the height of the rear just a tad to take up the slack from the extra 3/4 tire diameter. I know the stock tires on an early coach sit on the wheel wells. I just bought a set of 225 dunlop's so hopefully no issues with them..
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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