The results make it look like 5.29's would increase the rpm's by 170 at 70/5th gear, when they would actually only be increased by 60-70rpm's, on the other hand it looks like the the 4.88's would only lower the rpm's by about 70, when they actually lower the rpm's by about 170.

Very nice info Snowtoy, was fun to read all the differences. I thought about having the tire size select be a text field instead so the user could input his or her mounted size(s), but my prehistoric Determine your Actual Vehicle Speed calculator already does this. In the end I felt it reads better having the sizes listed. I added the metric sizes to provide for some variances between whole inch-numbers.

Regards,
BigMike