andysdesign3

planning to get some armano dumani 20s for my rl..they said 245/35 20...do u guys recommend 255/35 20???..ani diff..??..

Chas2

The 245/35-20 carries the closest rolling diameter to stock 245/50-17 wheel-tire combination. 255/35-20 has a larger diameter by more than one inch, which seems like too much to me. I like to keep it to less than a .5% difference, but that is just me.

All the car system calculations and how they interact, ABS, SHAWD, VSC, etc, are based on a certain rolling diameter, and you don't want to screw with that parameter too much, so I don't, especially since I am conservative by nature.

I seem to recall reading somewhere that more than 2% is unacceptable, but since I cannot find that reference, and since it was probably some internet reference, who knows how reliable that memory is? But others can chime in on their experiences.

Here are a couple of size calculators I use, one metric, one English.

http://www.carbibles.com/tyre_bible_pg2.html

http://www.miata.net/garage/tirecalc.html

Treblig

Here's another site you can add to the list.

http://www.1010tires.com/TireSizeCalculator.asp