I have to replace the rear tires and heard about some issue with the front diff getting chewed up with some people running 235/35/19 front and 295/30/19 rear. I have had this setup from day one on my Champion RG5 monolites and car always ran good and have had no problems.. Should I stick with the 295/30/19 or go with the recommended 315? Thanks

 

i dont know if i would recommend the 315. the 315 was the stock size on the gt2 with 12" rear wheels. the RG5s are 11.5" rear IIRC. I have heard that SOME people with lowered 996tts with gt2 spec wheels w/ 315 have had rubbing issues. Do you need the extra traction from the extra 20mm of tread?

 

i think you should be running 315/25/19's in the rear, thats what i have on my car and i have no LSD problems.

 

you NEED 315/25/19 for the rear and 235/35/19 for the front

on the 997 c4s
porsche uses 235/35/19 and 305/30/19 which is a taller tire than the 315..

 

I have the RG5's, H&R coilovers lowered about 1 inch, and run 315/25 19's and have no rubbing issues at all.

 

I have your exact rims. Run 315s all day with no issues. I even run 15mm spacers in the rear with rolled fenders... They come in 11 and 11.5" and both will work fine.

a 30 series tire will give you much better rim protection and ride at the expense of possibly damaging your viscous coupling, which you seem to be aware of and may have eliminated as a source of problems.

 

front diff getting chewed ????? I use the 295 but didnt know about that

 

I already told you what size's you need I wouldn't steer you wrong. Those 295's look so bad on the car.

 

I'm running 305s on my rear. Believe it or not they're a bit wider and taller than the 315s and I am seeing evidence of rubbing over rough pavement.
I haven't seen any PSM lights or any diff problems associated with these tires (knock on wood). However, my next set of tires will be 315s.

 

305/30 and 245 or 255/35 seem to be a decent match.

Not sure about fitment/rubbing in the front, but the increased diameter would be welcome in terms of rim protection and acclelaration IMO given the TTs ridiculously low first gear.

BTW I have some 255/30s on the stock 18" rims and they're a great match for stock sized rear tires. Better front end grip and fits just fine.

 

You want to keep the real diameter of the tires as close as possible front
to rear, if you go to the Tire Rack website you will be able to look up your
tires in the different sizes and it will show the diameter and revolutions per
mile for each size.

RD

 

+1... don't think it has anything to do with the width of the tire, it's keeping the ratio of the front and rear wheel diameters as similar as possible unless you have done the RWD converstion...

 

This was before I came to your shop.. I placed an order already for the 315's.. Thanks everyone..

 

so is it a confirmed that those size tires will definately be bad for the front diff or not?

 

even RWD will be affected by PSM and ABS issues if you have too much of a f/r mismatch.