255 vs 275

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jscott

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getting to the point of doing my rear wheel/tire remake.  I have new Cooper Cobra 215 x 60 15 on all four coruners right now.  Want to get an 8" Magnum 500 for the rear and new tires so wondering if 255  is the best for the 8" wheel and is 275 ok or is it pushing it on an 8" wheel? 

 
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I can't lay my hands on them right now, but there are charts for wheel / tire appropriate size combinations. You might find that with a Google search. You don't want a tire that bulges out past the rim too much.

 
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yeah, but math hurts my head lol.   I am thinking 255 might be the max for a an 8" wheel as the 275 may have the bulge problem
 I think you're probably right on the 255's. I run 245 60 R14's on 8" Magnums on mine (rears) and 235 60 R14 on the front on 7" rims. For me, that's plenty of tire for going around corners!

 

c9zx

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A 275 should have a 9 inch wide wheel as a minimum. The 275 will go on the 8 inch wheel but you won't gain much, if any, contact patch. Chuck

 

Hemikiller

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I'm running 15X8 all around, 4.25" backspace. 255/60 front, 275/60 rear. As Chuck noted, 8" is not ideal for a 275, but it's what I ended up with. 

IMAG3867X.jpg

 

mach71351c

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I went with 255/60s on 8s on the rear.  I feel there about perfect fit. The 275 are little big for 8" rims. Went with 245/60s on 7s up front.

IMG_2013.JPG

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IMG_2018.JPG

 

clevelandcoupe

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I am also running the 255/60/15 at the rear on a 8" rim. I agree they are the perfect size and look for our cars.

Thanks, Jay

 
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One more thing, don't forget that the taller the tire, it will affect the speedometer reading. It might be necessary to change the speedo drive gear. 

My 245 60 R14's at 60 mph on the speedo, matches the GPS reading exactly. However, I do not know if my speedo gear was changed before I bought this car.

As an example, on my daily driver, a VW Passat, the factory summer tires are 1 size larger than the winter tires I'm using up (off of a VW Jetta) and it lowers my actual speed by as much as 5mph at 60 mph. I have to watch my speed!!

 

jscott

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sooooooooooooo. 245's work on a 7" rim??

.........and what about 255 on a 7"?????  Looking at the tire store on a 255/60 15 it shows rim with between 6.5-9"????   https://www.discounttire.com/buy-tires/cooper-cobra-radial-gt

so, thinking now either 245 on my current 7" rims and if I do not like them I can always move them up front and get 8" rims with the 255 for the rear.............

 

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jscott

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that tire rack link also shows a 255 on a 7-9" rim as well

 

jscott

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I took a 3.5 hour ride up to Ponies in the Smokies yesterday to look over cars.  two things I wanted to see were tire size on 7173s and also looking for an aftermarket shift handle for my auto 2014 Mustang, I found neither really.  At the show there were over 1,000 cars with, in my estimation, 98% fox body and up, more like 80% 2004 and up.  Only 4 big nose Mustangs, 3 on the inside '71.72 and 73, special display so the fronts were roped off so you could only look into the engine bay and sides, thus I could not see the tire size on them.  the one on the outside (in the mists of the 1,000 cars outside) was a '72, clearly a daily daily driver.   But he had 295 on the rear which is not what I was looking to see.  I also noted the outside car and one inside both had the cowl braces missing, guess they like the look of them not installed. 

 

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I'm running 215/65 15 on the front and 275/60 15 on the rear both are on 8" rims.  Both sizes are rated to fit 8" rims.  Car handles well.

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