What will you say about these sizes ,
255/30/20 and 345/25/20 ?
I ordered 20" wheels and have to decide for the tire sizes soon , do you think 345 in rear will make problem ?

 

so you are going to add more weight, more rolling resistance and more understeer.... I dont think that would be a great idea

 

My BBS REs are 325 at the back I think.
If they are, they run fine so far.

 

DaBrat, can you confirm ? also, what is your FRONT tire size ?

 

Guys i have 345/25/20 and 245/30/20 and also have 245/35/19 and 325/30/19 its a perfect fitment have done countless 997TT with both no problems.

i actually did 345 1st ever in 2007 and that car still to this day has them over 50k miles not one problem with new owner .

here my car for reference https://www.6speedonline.com/forums/...00-horses.html
and 1st 997TT with 345 in 07 https://www.6speedonline.com/forums/...41r-997tt.html

 

345! Jebus those are some fat tires. I heard not to go beyond 325. Although I really haven't looked to see how much space is on the inside. This is weird, as there is a thread in the TT section about a guy running 315 on 19s and having all sorts of issues.

 

The problem was with the profile not the tread width. He was running 315/25-19 which is almost 4% diameter difference than the OEM of 305/30-19 - AWD didn't like that difference and was overheating.

 

Ahh that's right, thanks for following up.

 

100% correct 315/25/19 in so wrong ! on 997TT width inst the only part of equation .that every one needs to pay attention to .

 

Thanks Ben. I knew there are bunch of guys running these sizes without issues. I'm sure when manufacturing a tire each company will have small variances of like size tires as well. Some have more/less tread, rounder side walls..etc. All that can account for the difference in front to rear tire ratio. i.e. Michelin Pilot Cup may now have the exact same overall diameter as a Michelin PS2 of the same size.

 

thanks J.

 

Then I am ordering 345/25/20 and 255/30/20 ? Any one with objection ?
The awd ratio is also well with these sizes , it is about 0,97 .
Do you think 345's will be too big for the fenders ?

 

Quick search of '345' and came up with this.
https://www.6speedonline.com/forums/...00-horses.html

Are your wheels wide enough? To accomodate a 345, they'll have to be at least 13's. Offsets are equally important. 255's up front are mighty wide. I'm gonna guess they'll rub like no tomorrow.

 

Yup. Confirm. It's 325/30/19" rear. 245/35/19" front.

 

Most of you know this but for those that don't the wheel diameter calculator on the same site as offset calculator 1010 site makes math almost fun.