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need help(tire size)

1284 Views 8 Replies 6 Participants Last post by  dollarbill
i have 17 inch cobra wheels for a 89 mustang gt and i dont what size of tires to put in the rear cuz some said i could fit a 275 and some said i only could fit 245 but in a magazine i saw a fox body mustang with a 275 can some body help me please thanks
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87-93 cobra wheels are on sale on ebay WITH tires on them. they have 255's ON THE WHEEL in the pictures. so 255's are a definate. i can fit 245's on my 16" pony rims, and they are 7 inch wide wheels. if im not mistaken (all though i pro bably am) the cobra rims are 9 inches wide. you can definately fit some big meaty rubbers on there.
275s are 275 mm wide (otherwise known as 10.87 inches wide) while the 245s are 9.68 inches wide. (25.3mm = 1")

A 275mm 40 series tire is wider than a 245 but it's the same diameter as a 245mm 45 series tire. If your talking of staying in the same series, a 275 45 series will be a larger diameter than a 245 45 series.

275 ÷ 25.3=10.87 10.87 x .40=4.35 4.35+4.35+17=25.7" diameter tire
245 ÷ 25.3=9.68 9.68 x .45=4.36 4.36+4.36+17=25.72" diameter

Hopefully that helps you to understand the dimensional differences between the two. You'll have to get verification from someone else as to what will actually work on your car for sure.

I have 245/45/17s on my '95 on 9" wide rims. 275s on the same rims will work fine on mine and I've actually seen them installed on another '95. Don't know for sure on yours though........
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i have in mines is a 88' LX 17" cobra 99 rims with 245/45 on fron and 255/45 on back and no problems i think my rear tires are 26" right KK95GT?
and how is the convercion of the tires to know how wide they are in inches?
If you're running 275's in the rear then I believe they will rub. That's just my experience though. I had 275/40/zr17's in the rear and they tended to rub when in cornering, or my shocks just suck.
I think if you flip the quad shocks around then the 275s will fit. Not 100% on that thought. To use a 275 you need to have a 9 inch rim, an 8 or smaller won't cut it. I know that 245s will fit all the way around with no rubbing if your car isn't lowered. Big meats look sweet on stangs!!
26" is right

255mm ÷ 25.3 mm/in =10.08 inches wide

10.08 x .45 ratio = 4.54" tire sidewall height

4.54" + 4.54" + 17" = 26.08 outside diameter of tire

BF Goodrich shows 275/40/17s work best on 9" to 11" rims

One thing to remember, if you have ABS brakes, you need to keep the same tire diameter on all four wheels.
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they are 17in cobra from a 93 mustang how wide can i put the rear tire on this rims thanks
How wide is the rim. 17 X what? If its 8 inches, a 245, if its 9 inches a 275.
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