Eplebnista

I have a set of 17" Sport Classic rims that are 7 x 17 ET 55 in front and 8.5 X 17 ET 50 in the rear. I am thinking of 225/45R17 for the fronts and 245/40R17 for the rear. I could also fit a 255/40R17 on the rear. However, I am afraid that a 255 on the rear might look good but would result in understeer with the 225 being the max I could shoehorn on the fronts.

Any and all input or suggestions are welcome. The car is an 86.5.

Thanks

Vilhuer

225 and 255 was stock setup in GTS.

SMTCapeCod

So, did you locate some Cup Is?
Not sure of extent of hard use, but you can partially compensate by adjusting tire pressure.
I do autocross occasionally and we have the fun runs...I found it manageable when on 225/ET57 7" front and 265 ET47 9"rear,
---> Edit, oops those ^^ were 18s<---

and good with my current 245 on ET65 8" front and 255 on ET55 9" rear. I think you're probably right about sticking with 225 in the front..hey if you do get some understeer and aren't on a DE run, that's what the pedal on the right is for! :-)

docmirror

I'm looking into the same thing for my 88. I just test fitted a 255/40x17 on the front with a 7.5J-17 ET 47 rim and it fit well. Close to the inner liner on the front, but it did fit. I would say up to 245/40x17 on your ET would be ok.

Rear I test fit a 275/40x17 on a 9.5J-17 ET 53 rim and it was a good fit with no spacer. I'm goin to need to roll the fenders a bit or reduce the offset slightly. Since your rims are a little narrower, you might have to stick with 235 front 265 rear.

FredR

Doc,

I presume you meant to say a "225" on the front!

Rgds

Fred

docmirror

.....

FredR

A 255 on a 7.5 inch rim? - wow- I wonder how stable that would be. I cannot see how that would possibly work on a 47mm offset even if it was proven to be an acceptably wide rim. I wonder what the crowd make of that. With a 47mm ET rim you might just get a 235 in there but I would doubt any more than that not to mention killing the steering geometry.

Rgds

Fred

terry gt

the recommended rim for a 255 /40 / 17 is 8.5" to 10" according to the specs at tire rack

dr bob

Doc-- A lot depends on the actual tire, but 255 on 7.5's sounds like just a bit too wide for good support. Of course you'll have plenty of protection from curb rash. If it works for you and the way you use the car, go for it!

WyattsRide

I suggest NOT to go "Ghetto".....

docmirror

.....

Eplebnista

Rick:

You don't like these?

ThetaTau87

225/45R17 for the fronts and 245/40R17 for the rear is your best bet for balance and minimal understeer. These are the factory tire sizes for my '89 GT, but it had 8" wide front rims and 9" wide rears. Wider tires up front would lessen understeer, but you're limited by the 7" rim. You can physically mount wider tires than 225 on a 7" rim, but the bead will pull in the sidewalls of the tire compromising the contact patch of a wider tire and not give much if any more grip than a 225.

I currently have 225/45R17 front and 245/40R17 rear on 7" front and 9" rear Cup II rims. This gave too much understeer for my liking so I bought a pair of 8" front rims and will run 245/40R17 on all 4 corners.

Magnus Rostadmo

I would strongly advice you not to use these rim and tire dimenssion.
Biggest problem here is that you want to use a rim that has Et47.
This rim will maybe fit with that tier width, but you should not use it.
Your car will not be stable at all. May be to an extent that can become dangerous especially in a critical situation because this rim has an ET that is way to low.
Add a tire which is to wide for this rim widht on top of that, and your car may exhibit some very "interesting" handling.

I will advice you to read this for starters: http://www.landsharkoz.com/forms/928wheels.pdf

And search this forum for negative scrub radius or Wheel fitment 928. There is more to wheel and tire fitment than just to be able to bolt it on.

Neil Forn

I'm running 245/40-17 on 7.5 rims in the front and 275/40-17 on 9.5 rims in the back. (going by memory on the wheel widths)

The fronts are too wide for the rims. The sidewalls are really bulging out. Under normal conditions it drives ok but I think it could be better under hard cornering.

The rears look awesomely wide from behind and fit the fenders without problems. However, the tires are a little taller and the car doesn't feel as quick. Highway mileage might have improved, which is what you would expect by raising the effective gear ratio.

The next set of tires I buy will narrower in the front and a lower aspect ratio number in the rear.