MJFuss

My '89 M6 Coupe needs tires and I dislike the look of the wheels (which are not in great shape either).

I found locally a set of nice AFS GS replicas with newer tires for under $600. I suspect I could get them for $500.

I like the look of the GS wheels, and I like the weight savings, but I'm worried about compromising the handling of the car by adding wider tires in the back.

Will the handling of the car be better, worse, or the same with the new wheels (all else being equal)?

This car is a daily driver, autocross, and occasional track-day. The suspension is stock, the motor is pretty close to stock, but will see some power upgrades in the future.

Thanks.

kmillar

Are the rims 17x9.5 and 17x11?The increased tire/rim width isn't a issue Performance wise, but if you're running the 17x11 out back there may be a issue with the tire sticking out beyond the wheel well.
Before you purchase check out the tire sizes available and what type (manufacturer ).
The 315 rears are around but for a good auto cross tire you may be limited
Do a search there are a lot of threads discussing this

dizwiz24

I dont think you will be getting a weight savings with replica GS wheels.

Typically replica wheels have to be cast thicker because they arent as dense/ or the metal is inferior to an OE wheel.

While the OE grand sport wheels are not true forged wheels, they are borderline 'forged' using a Roto-mold process to increase the density of the casting / can therefore be cast thinner to save weight.

I wouldnt be worried about the tires sticking out.

I have 17x11 and 17x9.5 GS A-molds on my 93 and its not too bad.

MJFuss

I know that the AFS replicas are not as light as the OE GS wheels, but, according to various discussions on this forum, they are within a couple of pounds. The 88-89 wheels are heavy.

I'm not worried about the wheels sticking out, but I'm a little worried about adding more understeer that I'll have to 'tune' out somehow. Most of the track/autocross guys seem to run a square setup with 275/40s all the way around.

Thanks for the feedback.

c4cruiser

With a 17x9.5" wheel and 275/40 tires, you will get to rotate tires for longer tread life. And there are a number of good high-performance tires available in that size.

For the 315/35 tire on a 17x11 wheel, I have seen some C4 autocross cars with that tire/wheel combo on all 4 corners, but those guys typically run A6's.

The 315/35 tire is getting harder to find so you should consider that for future tire purchases.

Deakins

Yeah I ended up going with some chromed OE C5 Z06 wheels for my 93 as the 315's have become a little difficult to find if you are looking at street tire options. The 295/18's are not a lot better but there are more options as of now. Something to thing about; but I do love the 315's on the back....

Joe C

I have 9.5" AFS ZR-1 replicas on all four corners on my 85. they've been on for years, and I've never had an issue with them. personally, I'd stick with the 9.5's all the way around for the convenience of having the same size tires. don't forget the correct offset when buying late model C4 wheels for an early car.

scotth48

I have Detroit Z06 wheels on my '93. I like the fact they are 9.5" and tires can be rotated. I would like to have ZR1 spoke wheels.