When you buy a tune from brenspeed or bamachip, they ask you for your tire size . What is the purpose of this? Would your car run into any problem if you ran the wrong tire size tune? I requested a tune update for the tires recently and I don't know if he sent me the updated tune or same old ones. How would you find out which tire size is in the tune?

 

My guess is so that your speedometer is right. It doesn't really have any effect on the performance of the car, but rather tells the computer how many rev/mile your tires are using.

 

What tuner are you using? Also If its a predator tuner I think you can change the rev per mile yourself on a custom tune. Just get the rev per mile from the tire manufacturer and DO NOT use predators formula for figuring it out in the user manual, it is way off.