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I thought I’d ask this question in here given 996 GT3 is so similar to 996 cup and folks in here are a bit more "experimental" in their endeavours with these cars. I have some new slicks that I want to try out but the actual sizes run wider than quoted. It’s supposedly a 250/640-18 but actual tread width is closer to 260mm and the section width is 280mm! As you can imagine the shoulders are quite rounded, which should help fitment. I don’t mind if it rubs the plastic fender lining but obviously a cut tire or damaged body work is less desirable.
Before I *try* to fit them up, I thought I’d ask if anyone has pushed the envelope with front tire width on a 996 GT3? I would like to know what the maximum width is for the front of these cars. I ran 245/40 NT01 on my road car but I think I could have gone wider with a wider rim. I am running -5.2 camber on the front of my cup car so fender clearance *shouldn't* be an issue but would be good to know what to expect.
It's really all going to depend on a few different factors....I've been researching this in quest of a larger front footprint for my car I'm going to attempt in the off season.
What wheel width - if you're going to try to put those on a stock 9" cup front wheel I bet they are going to bubble even more on the sidewall and spring clearance is going to be your limiting factor.
Wheel offset - you want to get more aggressive with offset to put the tire closer to the fender as you're going to run out of room on the inside of the tire where it will hit the spring. I've seen as aggressive as 36 offset and some claim they can get away with a 265-275 tire on up to a 44 offset 10" wheel on the front.
What diameter spring (You really need them to be 2.25" diameter for the best shot of this working, but I've seen it done with a 2.5" spring. Every little bit counts)
Ride is also potentially going to contribute but with -5 degrees of camber you're going to have more fender clearance than most.
Top mount camber plate orientation is a consideration on street cars but probably not yours.
On street cars it's likely you're going to need to move radiator brackets forward and trim fender lining..again may not be an issue on a cup.
I can think of 2 forum members that have 275 nitto's on the front of their car which have a section width right about where those slicks are. It can work, the question is how much of the above will you have to go through to make it work.
Thanks for the replies. So it’s definitely possible but more work than im prepared to do to run these tires. I’ll just send them back and try their 240 instead.
I run 275 on a 10” front. Tire is 645 tall, 292 cross section. Front ride height set at 100
I measured the tire again and it’s pretty much bang on with your measurements, except ~635 tall. What is the clearance to the spring on the inside in your set up? I suspect the narrow cup 9 inch wheel and lower ride height would undo me as Andy suggested above. I’ve arrange to send the tires back but it’s good to know they’re not far off being able to work.
I measured the tire again and it’s pretty much bang on with your measurements, except ~635 tall. What is the clearance to the spring on the inside in your set up? I suspect the narrow cup 9 inch wheel and lower ride height would undo me as Andy suggested above. I’ve arrange to send the tires back but it’s good to know they’re not far off being able to work.
With 5" long 2.25" I.D. spring the clearance was about 4mm between the inner lip of the wheel and the spring perch when using the standard 996GT3/Cup uprights. On my new set up I'm using 4" mains which places the whole spring stack higher up on the shock body thus creating more clearance. Spring thickness will also play a factor. I run 1700 lb front springs which are a little larger outer diameter due to the thicker coil wire than what you would have on a thinner softer spring so all that will determine your final inner spring to tire clearance. Everything has to be taken into consideration as fitment is very tight. I can probably snap a pic in the next day from underneath as my car is on the lift at the shop.
With 5" long 2.25" I.D. spring the clearance was about 4mm between the inner lip of the wheel and the spring perch when using the standard 996GT3/Cup uprights. On my new set up I'm using 4" mains which places the whole spring stack higher up on the shock body thus creating more clearance. Spring thickness will also play a factor. I run 1700 lb front springs which are a little larger outer diameter due to the thicker coil wire than what you would have on a thinner softer spring so all that will determine your final inner spring to tire clearance. Everything has to be taken into consideration as fitment is very tight. I can probably snap a pic in the next day from underneath as my car is on the lift at the shop.
Thanks for the info. I suspect it would be too tight on the cup car given the wheel offset, then again you're running a wider wheel which probably runs closer to the spring anyhow.
powdrhoud, is your car the NB or wider Mk 2 body? I'm trying to fit a 255/35/R18 Hoosier R7 on a 9" rim on my 996 C2 NB based race car and I'm wondering if it will work. I think it will but my 245/40/R18 BFG R1 is already a pretty tight fit. I've got about 12mm of clearance to the spring perch as it sits today. The 255/35 R7 seems pretty wide; it has the same tread width as the 275 and a 10.8" section width on a 9" rim according to Hoosier's specs.
Running JRZ RS coilovers and GT3 LCAs but not sure what the spring diameter is. I'm wondering how much of a difference to the relative inner vs. outer positioning the stock C2 uprights make vs. the GT3.
powdrhoud, is your car the NB or wider Mk 2 body? I'm trying to fit a 255/35/R18 Hoosier R7 on a 9" rim on my 996 C2 NB based race car and I'm wondering if it will work. I think it will but my 245/40/R18 BFG R1 is already a pretty tight fit. I've got about 12mm of clearance to the spring perch as it sits today. The 255/35 R7 seems pretty wide; it has the same tread width as the 275 and a 10.8" section width on a 9" rim according to Hoosier's specs.
Running JRZ RS coilovers and GT3 LCAs but not sure what the spring diameter is. I'm wondering how much of a difference to the relative inner vs. outer positioning the stock C2 uprights make vs. the GT3.
09-27-2018, 02:26 AM
Max front tire width? 996 GT3
