Paulsha911

I searched thru the forum but can't find the exact combination. Can someone tell me if this will work:

97 C4S, PSS9 lowered to Euro RS spec

BBS RS GT
8" x 18" - ET50
11" x 18" - ET45

Michelin PS2
245/35/18
295/30/18

The other possible combo seems to be S03
235/40/18
285/30/18

It seems both PS2 and S03 combos will give me similar front rear stagger ratio. But 295 might give more curb protection for the 11" rear. But is 245/35 too big for the front?

The S03 combo is also about $250 cheaper...

Thanks in advance.

David in LA

Your car is a C4S so you also need to make sure neither one of these combos is too far off from the stock 225-40/285-30 with regards to relative front/rear diameters..otherwise you can damage your viscious coupling and I think someone had previously posted that it may affect your anti-lock brakes.

Paulsha911

Dave:

I think there are two factors. The front/rear diameters cannot be more than 5% apart (for the AWD), the the front/rear stagger ratio would affect over/understeer. Right?

According to my little excel spreadsheet, the f/r diameters are okay with both combos. The stock f/r stagger ratio (rear divided by front) is 1.266. The 245/295 combo is 1.204 and the 235/285 combo is 1.212. I could go 235/295 but there is only one tire choice that would work.

Am I doing this right?

Acropora

I've run 235/295 ps2's on stock rims w/o rubbing.

Paulsha911

Thanks Acropora. The 235/295 f/r stagger ratio is very close to stock. I am looking for something that will reduce the understeer... That's why I was thinking 245/295 or 235/285...

DJF1

The PS2 sizes you have are absolutely fine. The difference is .2 of an inch on the diameter so this is not an issue. I honestly do not recommend the S03, I have it on my M3 and its a horrible tire
You could also go with the new Yoko Advan Neova with sizes 235/40 and 295/30. I have heard recently raving reviews on this tire and I maybe going this way next.
Also bear in mind that a few people here with a wide body have fit 305's and 315's back there....

DJF1

While a larger size fronts will help, what will make a difference are your sways and the setup of the car. How much negative camber in the front VS rear,toe in/out, shocks etc...

David in LA

That sounds right. Regarding the understeer, with your RS sway bars you should be able to dial the understeer out. Post pics when you get the wheels...I'm a big fan of white 993s!