bluovalguy

I just picked up a sct x3 for a good price (thanks Jason!), and have a question about custom tunes. It might be dumb, but I would rather ask a dumb question than not get what I want.

Bamachips site ask for tire size. I am assuming this is only to correct the speedo. The reason I ask is because I run two different sets of tires, the stock 17's for winter and the heavy rainy season here, and then staggered 20's the other 6-8 months. Is this going to matter at all, or am I right in assuming it is just to adjust the speedo? Thanks in advance!

gt/cs07

From my understanding it is just to correct the speedo.

Lifter583

You will have to know the revs of each tire size and then you can make the change with the tuner to match the speedo with the tire size.

bluovalguy

Thats what I was thinking, just wanted to make sure. Thanks all.

Nuke

+1

When you swap to a different tire, just plug in the tuner and make the appropriate tire revs per mile correction.

bluovalguy

According to the tire size calculator there is only a 1 mph difference between my two sets, so I wont even worry about it.

Nuke

My speedometer, from the factory before my tire size change was off by about 1.5 MPH according to my GPS. Even AFTER my tire change and adjusting the revs per mile with the handheld, I was still off by about the same. My xCal 2 only allows revs per mile changes by tens of miles (i.e., 730, 740, 750, etc) so I can never get it dead-on. No problem, though.