What exactly failed? The diff or the viscous coupling?

 

the mechanic said the whole diff had to be replaced. The gear oil all came out and the axles were flopping around inside. He said if I kept driving it the front would have locked up and caused damage in the rear via the drive shaft.

 

My experience is you will have trouble (psm, abs, front diff etc) with a 996 tt with 19" wheels with any tire combination other than 235-35-19, 315-25-19. Having said that, my problem is I need tires and I can not find any 315-25-19s anywhere. No Michelins, Nittos, Yokohamas or anything else. Has anyone else been able to locate any? If so, please share.

 

Sorry to hear about your differential. I have an extra if you need a good deal on one. I am in CO, but freight shouldn't be too bad, especially with a deal :-)

 

See if all the members that pu pu the concerns about mismatch as "not a problem" followed by "mine had no issues" will chip in and pay your bill.

 

Now that's funny!!! 235-35-19's and 315-25-19's here!

 

^ideally that's what I'd like to do, now Michelin needs to hurry up and make the PSS in that size so I won't need to run mismatched tires! I won half off a set of custom built wheels at MFEST while in Vegas though, so I'm going to be running 19x8.5 and 19x12 with a nice concave profile.

 

Nice score at mfest.

I run 9" rims up front- allows for 265/35 or 235/40... with 315/30 on the rears. 18". The change from 8.5 to 9 was a no brainer.

 

I am switching to 295/35/18 rears and 245/40/18 fronts tomorrow,Conti DWs are a great price..And I like the bigger side wall and higher ride height...Chicago streets arent the best..
Thats only a .4'' diameter difference..I ran .5" difference for 22,000+ miles with ZERO diff. problems,And routine tech inspections....

 

295 30 19 and I fit on some 245 35 19's on front by a millimeter or two. Still no rub! Only one rotation/mile more than stock with that set-up on Hankook evos. Not a hint of PSM light anymore! Feel good too.

 

what about 245/35/19 and 305/30/19?

And What if I have a 12" rear wheel? I have 997 GT3 wheels....

 

is there a wider comparable diameter tire for 19"? I'd go wider up front in a heartbeat as long as the diff holds out!

 

to answer my own question...I was looking at the size specs and this is what I'm seeing...

stock: 225/40/18, 295/30/19 with a 3 rotation per mile variance.
current: 235/35/19, 305/30/19 with a 25 rotation per mile variance.

possible solution: keep my back MPSS and replace the front with 265/35/19 which is the same diameter as the rears and only has a 2 rotation per mile variance.

now...is that front tire going to be too wide? TR says the approved rim width is 9-10.5

is anyone running wider than 9" up front without rolling fenders?

 

225/40/19 is better match with 305/30/19 than 245/35 unless you can fit 265/35 in front or find a set of 315/25/19 in rear. Why? Please read the following posted by Thale and pwdrhound:

https://www.6speedonline.com/forums/...rubbing-4.html

 

I'm pretty sure he was referring to those running the 305/30 size in the rear. The sizes you are running are fine. The only problem with your size is tire choice right now. If you can even find them in stock, there are like two options.