Running Different Size Tires - Problem???
Thread Starter
Instructor
Joined: Sep 2005
Posts: 185
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From: Buckner Missouri
Running Different Size Tires - Problem???
A couple of months back someone told me that running different size tires on the rear would cause me rear end problems. I'm speaking of the milage to get home or a shop after having a flat.
I'm running 245/60/15 on the front and 255/60/15 on the rear. If I use the 245/60 as a spare and need to put it on the rear to get home or to a shop am I causing myself problems? The drive on the spare could be 100 miles, not likely I'm gonna be that far from home but it is possible. I could use the 255/60 for the spare but think it would be very tight if used on the front. The 245 has rubbed when backing out of the garage while turning tight uphill. Don't want to run the 255 on the front.
Anyhow will a 255 on one side and a 245 on the other side in the rear cause me problems if being driven to get home? For sure or is it a guess either way?
I'm running 245/60/15 on the front and 255/60/15 on the rear. If I use the 245/60 as a spare and need to put it on the rear to get home or to a shop am I causing myself problems? The drive on the spare could be 100 miles, not likely I'm gonna be that far from home but it is possible. I could use the 255/60 for the spare but think it would be very tight if used on the front. The 245 has rubbed when backing out of the garage while turning tight uphill. Don't want to run the 255 on the front.
Anyhow will a 255 on one side and a 245 on the other side in the rear cause me problems if being driven to get home? For sure or is it a guess either way?
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
There is a tire diameter table on www.tirerack.com
This is not very exact (f.e. they advertise my 255-60-15 tires to be 27.2" diameter, I measure 26.6") --- I also have 245-60 Dunlops that they advertize to be 26.6", I measure 26"
The diameters are not exact but the difference between the two is
.600" difference in diameter is only .300" on the radius, I doubt that that will cause any damage to your differential or other components...
I'd get a cheap 225-70-15 tire to use as a spare, it's advertized to be 27.1" to match the 255-60-15's diameter and is narrow enough to fit your front...
This is not very exact (f.e. they advertise my 255-60-15 tires to be 27.2" diameter, I measure 26.6") --- I also have 245-60 Dunlops that they advertize to be 26.6", I measure 26"
The diameters are not exact but the difference between the two is
.600" difference in diameter is only .300" on the radius, I doubt that that will cause any damage to your differential or other components...
I'd get a cheap 225-70-15 tire to use as a spare, it's advertized to be 27.1" to match the 255-60-15's diameter and is narrow enough to fit your front...
Safety Car
Joined: Oct 2004
Posts: 3,927
Likes: 740
From: Youngstown Ohio
I've never done it on my Vette, but my Regal has a "donut" spare that is way, way, smaller than the regular sized tire and I've used it with no problems......so I wouldn't worry about an inch or so difference. But it's not recommended for more than 50 miles or so before changing.
Pro
Joined: Jan 2005
Posts: 539
Likes: 3
From: Twin Cities Minnesota
jus my $.02 but I think the concern on a vett is Posi on the back, with 2 diff sizes you are turning at different rates, on a standard car you dont have posi. Still not sure how much of a problem between a 245 and a 255 but I think I would not try to go too much different for too long..
Thread Starter
Instructor
Joined: Sep 2005
Posts: 185
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From: Buckner Missouri
"jus my $.02 but I think the concern on a vett is Posi on the back"
76Project, I believe you're right I recall the earlier concern was with the Posi on the rear. I like RedBad79's idea about the 225 matching the rear 255's and also fitting the front OK.
Stroker, does the Regal have Posi-trac?
And Yep, my main concern is just getting home. Not something I can run as a regular tire.
76Project, I believe you're right I recall the earlier concern was with the Posi on the rear. I like RedBad79's idea about the 225 matching the rear 255's and also fitting the front OK.
Stroker, does the Regal have Posi-trac?
And Yep, my main concern is just getting home. Not something I can run as a regular tire.
Last edited by Blue 74; Dec 19, 2005 at 11:47 PM.
Safety Car
Joined: Oct 2004
Posts: 3,927
Likes: 740
From: Youngstown Ohio
Originally Posted by Blue 74
"jus my $.02 but I think the concern on a vett is Posi on the back"
76Project, I believe you're right I recall the earlier concern was with the Posi on the rear. I like RedBad79's idea about the 225 matching the rear 255's and also fitting the front OK.
Stroker, does the Regal have Posi-trac?
And Yep, my main concern is just getting home. Not something I can run as a regular tire.
76Project, I believe you're right I recall the earlier concern was with the Posi on the rear. I like RedBad79's idea about the 225 matching the rear 255's and also fitting the front OK.
Stroker, does the Regal have Posi-trac?
And Yep, my main concern is just getting home. Not something I can run as a regular tire.
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Instructor
Joined: Jun 2005
Posts: 109
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From: NH
Shouldn't be a problem, Yes you have a posi-but it's not like you have a locker. Your rear tires spin at different speeds any time you are turning a corner anyway, and that doesn't cause a problem. So using a slightly smaller spare for a short trip shouldn't be a problem.
Or just carry a can of fix-a-flat.
Or just carry a can of fix-a-flat.
Safety Car
Joined: Oct 2004
Posts: 3,927
Likes: 740
From: Youngstown Ohio
I just checked and sure enough, my TransAm GTA with 3.42 Posi rear came equipped with the small "donut" spare, also. So it shouldn't hurt posi rears. However, the manual does give a warning to use it for no more than 50 miles or so.
