The increased OD would make my speedometer read MORE accurately.

 

Are those offsets for 18 inch or 19 inch rims? What rim & tire size are you running in the front?

 

What is RuF running on the RT12? I think they are using 19"s with like 265's in the front and 355's in the rear. Then again, they are probably tubbing out the front and rear wheel wells to run that big...................

 

MARSKI, were the 335's you tried rubbing on the inside?
I have 315's on stock ET45 11" rims. They are very close to rubbing on the inside rear wheel well liner over the turbo hose connector. The tire section width is 12.5". 335/30-18's on a 12" rim have a 13.3 - 13.5" section width. Almost all the extra width of 335's will have to go to the outside. I think it would take a wheel with an offset of ET25 to ET20 . This extra 1-1.5" of extra outboard tire width might rub too much on the fender lip, even if you roll it. A GT2 ET40 wheel with a 15mm spacer might fit.
Seems like Sharky was running 335's, but was rubbing holes in his fender liners.

 

Why? It is so silly to assume it's going to do anything for you. You're better of changing the suspension geometry in effort to gain performance than silly tires.

 

These cars have LOTS of weight on the rear tires. IMO the rear tire size is a limiting factor.

 

The only 25 series I have seen to date is a 355/25/19 Might be worth looking into.