LT1

I'm going to purchase some SSR GT3 rims.

Rear 295/30/18 on 10.5" rims (35mm offset)
Front 225/40/18 on 8.5" rims (47mm offset)

Should I run 235's up front?

My car sits at about 25" from ground to apex of wheel arch.

jmayzurk

LT1,

I have 8.5x18 (47mm) and 11x18 Kinesis K-28s on my car. I run 235/40 and 295/30 Michelin PS2s. I am at RS ride height, which is a little less than 25" in the front.

When I first put on the wheels and tires, I had a little rubbing on severe dips. Since then, I've rolled the fenders ever-so-slightly (the old baseball bat method) and gone with more front camber (-1.7 deg), and there's no rubbing whatsoever.





One word of caution: My father had SSR GT3s on his 928 GTS, and he had recurring problems with cracking on the rear wheels. Apparently these wheels are no longer available new, so don't count on replacements being available...

-Jeff

LT1

Jeff

I was hoping the someone with a lower suspension would reply. I love your stance and 'dished' wheel look--something I'm trying to achieve with the SSR's. I appreciate the heads up on the wheels. I have heard of SSR and other wheel manufacturers with these types of issues. Damon at tire rack thinks that some of the negativity concerning the SSR's is overblown and that their build quality is definately no worse than lots of wheels and maybe better. If i cant get a replacement wheel in the future that would suck.

LT1

Since I posted this thread, I have used '993 pilot's' wheel and tire fitment spreadsheet and I must give props as it is an EXCELLENT tool to help with clearance/offset/aspect ratio questions.

LT1

[QUOTE=jmayzurk]LT1,

I have 8.5x18 (47mm) and 11x18 Kinesis K-28s on my car. I run 235/40 and 295/30 Michelin PS2s. I am at RS ride height, which is a little less than 25" in the front.

Jeff Are your rear arches at around 25"? Do you know the offset on your rears? Thanks again

drgn2phnx

Man,.......
With the tire 5mm wider on each side, (10mm wider than the 225's)
I think 235s will do the rubbing thing inside or out....
My car sits pretty low as well, am running 235s, too
rubbing occured when pulling hard on corners, both sides
I really don't think 235's are right for the front~
235s are too wide

vrus

The 225/285 combination coupled with a very low suspension (ie. coilover) already exhibits a fair amount of tram-lining.. Why would you want to step up the tire sizes and make it worse? If it was a RWD car I would say bump the tires +1 size, but on a 993TT which is AWD, 225/285 works just fine. There is no added benefit to having a 295 rear on this car since traction is not an issue to being with.

Also, on my previous car, with my H&R coilovers set to a very low setting, I had to install the bump-steer kit in order to keep the car moving in a straight line on uneven highway.

My $0.02...

jmayzurk

In my experience tramlining is largely a function of alignment and tire brand (e.g., Bridgestone SO3s tramline a lot but Michelin PS2s not so much). Sure, wider tires will exacerbate the problem, but 10mm is not going to make a significant difference.

As for grip and traction, I guess it depends on how you use the car. Personally I think the 993tt understeers too much; in my opinion you can't get enough front tire on these cars. Furthermore, my car with only light modifications (UMW stage 1 kit) easily overwhelms the grip of my 295-width PS2s.

There are some guys around here running 255s on the front, but I don't know how they make them fit.

LT1, my rear wheels are ET41, and there's plenty of room on both sides for more tire.

jmayzurk

I just measured. My rear floor-to-fender measurement is exactly 25". The FR (first pic below) is exactly 25", and the FL is 24.75". And my car is corner-weighted to a 40lb cross weight.

Here are some close up pics of tire-to-fender clearance. Sorry for the dirty car.




Though I am happy with this setup, I caution you to expect some rubbing with 235s in the front unless you do some minor fender rolling and have a fair amount of negative camber.

Bradford

I run 245/19's on the front (very low) and have a slight rub. My fenders are rolled.

DM993tt

I run 265/315 on mine (silver) & -2.5 camber. The car much lower than RS spec.

Turbodan

I've got gemballa suspension and wheel arch is exactly 25" at the highest point in front
my advan 048 s are 235 40 18 up front with no rubbing whatsoever (new tires), no rubbing at track either.

vrus

Guys dont forget one thing.. Not all tires are created equal.. A 235 Michelin PS2 is going to be wider than a 235 Bridgestone S02.

Also, the rim backspacing, rim width, and offset are all going to affect how the tire sits in relation to the fenderwell and its surroundings so remember not to compare what someone else is running for tires unless you have the same wheel & suspension setup.

A 295 tire is optimal for a 10.5" rim.. On a 10" rim its going to bulge a bit more and may cause contact problems with a fender (ie on a stock 993 wheel).. On an 11" wheel, the tire will be stretched a bit more, and will pull the tread inward away from the fender which provides a bit more clearance.

So, if you are running stock 993TT wheels, I would recommend you stick with your 285 in the back. Anything more than that and you are just going to bulge the sidewalls.. I dont think you will end up with any greater a contact patch than the stock 285.

LT1

Dan: Do you know your rear offset? Your sig says 19" hre yet your post says 18"? I'm curious because I like the black spokes/polished rim look

LT1

I think your rear offset et41 is perfect for 993tt lowered to around 25" I think I can go offset between 35-42 ish for a 10-11" rear rim with 295 or smaller tires. I'm going to try my brothers 996tt rears (11" with 295 and 35 offset) to see if I get any tire rub. What exactly do you mean by "tram-line"

-Larry