Hi All

I need to buy some new tyres. I have 15x7 rims on my firebird which currently has 215/65 tyres on.

I would like to put some larger ones on the rear, something like 225 or 235, what is the correct height I need ?

Thanks
Geoff

First of all it's tires. Second I have 235/60/15's on my 15X7's and they look great.

well i was in the same place as u when my friend wanted to get tires (or tyres) on his Z28 with 15x7 wheels. We didnt wanna go to wide or it would look stupid and we did want to drop the profile a little bit to compinsate for increased width. The perfect size tire for those is a 225 60 15 compared to the factory 215 65 15. I would advise against mismatching tires, if u replace 2 u might as well wait for all 4. it will look a whole lot better and will pay off in the long run......

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1989 pontiac firebird
bright red exterior(just repainted)
grey interior
5 spd
305 TBI (stock)
WS.6 formula wheels
3.73 posi rear end
http://members.aol.com/j007golden/Mikey89.html
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1985 trans am
factory bright yellow
4 wheel disks
16 inch wheels
305 TPI
power antenna and mirrors
t tops

you can put 255/60/15's on those rims. they look pretty wide, i think mine were 60 series but when i did that the speedo went off by 7 mph, so you might want to try to get some 55 series instead of the 60 series.

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Brandon
"ScreaminDeamin 360"
350 60 over, TRW forged 9.83:1 pistons,Hooker Comp headers, crane cam 216/228 .484/.512, crane 1.6 RR's, ported plenum, home made ram air, 24lb SVO injectors, crane AFPR, all going through 3 inch mandrel pipe and a flowmaster.
New project-89 IROC
Soon- 6 speed, Pro 5.0 shifter and 4.10's
http://users.argolink.net/bvana

http://ScreaminDeamin.cz28.com

It's "tyres" across the pond, my friend.

235/60/15 is the correct tire for maintaining the 26" overall diameter of the stock tire.

As Jza says it's tyres in the UK

Does rolling circumference make any difference ?

Geoff

Yeah. Shorter tires "act" like shorter gears (numerically higher). Obviously that throws off the speedometer some. Plus anything less than 26 inches in an F-Body wheelwell just looks lacking.

Try this site, it should answer everyone's questions about Tyres
http://www.miata.net/garage/tirecalc.html



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"It's not about going fast all the time; It's knowing you can, anytime"

Wow, Imark. That's a hell of a calculator!