Will 295/35-18's rear tires fit with stock size front tires without damaging the front differential?

 

Not sure why you want to go from 30 to 35.

If you are wanting more sidewall for a softer ride, stock GT2 size tires. 235/40/18 and 315/30/18 will work on the stock 996TT wheels.

 

check tire diameter and do the math!

 

There are two things to consider.

Will it fit the wheel (and wheel well).
Is the size (Diameter or Rev/mile) within 3% of each other Front to Rear.

Someone please correct me if the 3% is wrong.

Use actual specs published by the manufacturer, not a tire "calculator".

 

295/35 will fit not problem but I wouldn't run them with the stock fronts. I bought a set of 295/35 rear snow tires but I matched them with 225/45 fronts.

 

HI,I have been running 285/35/18[25.9] rears and 235/40/18[25.4] for over 22,000 miles now without a problem,,,,as I have stated in detail in past posts and threads on this dia. topic......I was going to run 295/35/18[26.1] which will fit ... But ONLY if I could run 245/40/18[25.7] fronts...I never followed up myself to find that out with the fronts...I think going to a 295/35 rear with a 225/40[25.1] front is way out of wack??Plus the car would sit funny??.....But then again people thought that with my combo.......lol.....Good Luck....

 

I wouldn't run that big of a mismatch between front and rear.

 

My general comment is that if you stray from the tire sizes Porsche states in the owners manual or even if you stick with these tire sizes but move to non N-rated tires you run the risk of fitting a set of tires that could have sufficient diameter differences to the point the front diff or the fluid coupling or the cardan shaft even is damaged.

(The non N-rated tires may have different sidewall stiffness and the effective tire diameter different enough even though the tire diameter calcuations indicate the diameters are within the acceptable range.)

Sincerely,

Macster.