I whipped up a quick spreadsheet in MS Excel that allows you to enter tire sizing and calulates overall diameter and % error. So, if you guys have MS Excel, check it out. If there are any problems with it let me know.

http://www.glue.umd.edu/~nauman/tire_calc.xls

 

It works just fine. How about showing the speedometer difference between the original and new tire size at a couple of speeds? Say 30, 60 and 90 mph. Why did you leave the overall diamter in millimeters? Just curious.

 

Thanx dude!

 

Not to diss your spreadsheet or anything... but there's also a website where you can calculate tire sizing.

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

 

yeah, i know....

but, this way you can D/L this thing to your computer and then use it when you are not on the net

Just a dumb idea I had

beaglemax: hmmm....the speedo difference at different speeds would require a bit more....I probably need to know gear ratios and such for that....I left it in mm beacuse I like metric

 

UMD_MaxSE

I think that esimating the speedometer differences can be accomplished neglecting gearing. The speedometer reading is related to the number of revolutoins of the wheel in a given amount of time. It should be as simple as finding the percent difference in circumference and relating this to the observed speedometer reading.

 

yeah....i think you are right....it should not be that hard then....I'll think of it in my spare time

 

Slacker. Nice job.

 

hehe.... thanx....

i'll think of it this weekend....i'm at work now thinking of work related things and mindlessly posting