so i'm getting this wheel/tire set for really cheap but the tires are gigantic. they're kumho ecsta 245/40/18. the guy had it on his a4 but idk if was lowered and it rubs the fender in the rear. also the tire calculator says i'll be doing about 2mph faster than what i would be doing. i was wondering if there's a way to adjust the speedo reading with vag com or something to change that to normalize the reading. i know it can be done with dodges as my friend got 20" wheels for his durango and did that with a tool that connects to the obd.

 

I really wouldn't worry about 2mph +/- either way. Not sure if you can VAG it or not, but i would think you would need a tech and a dyno to accomplish, but idk.

If you ran summer and winter rims/tires, you would have to do this everytime.....hardly seems worth it. If you're that concerned about the mph variation, just buy some 225/40/18s; it may be cheaper in the long run, but again, idk

 

i've got 19s and everytime i go by one of those police speed check things in the middle of the road it reads exaclty what speed i am doing...i thought the bigger wheel would make a difference in my speedometer reading but i guess it didnt.

 

wut tires you running?

 

The width of the tire doesn't affect the speedo, just the diameter. For instance if you had a 20" wheel then it might be a 2-5 mph difference.