Fellow listers and spring fever afficianados,
Having completed my O/D conversion, 3.89 diff installation and various
and sundry other items during the off season, I have come to realise my
speedometer is off close to 12.5%. I scientifically came to this conlusion by
realizing my normal 45 mile one way trip to work now showed 39.5 miles on my
odometer, and through the fact that when the CHP pulled up next to me and asked
if I realized that I was doing eighty, at which point my speedo read 70.
Now logically, the best thing to do would be to have the speedo
recalibrated. However, since I will be adding wire wheels later this summer,
I'm thinkin' (I know, scary- hunh?) I can accomplish this adjustment by
changing the profile of the skins fitted to said wheels.
I am currently running Bridgestone 185/70 HR 13's on the stock steel
wheels. They seem a might bit tall in the wheel wells for my liking. Using
the tire size page on the web (http://www.powerdog.com/tiresize.cgi) I have
found that the circumference difference between the 185/70's and the 185/50's
Am I to assume that this number will translate straight across to the
speedo? ie. will a -12.6% difference in circumference create a -12.6% change
in the speedo reading?
Also, will there be a problem using this profile tire on a standard 13"
x 4.5" wire wheel? Should I get a wider rim? Which other TR's have the same
size lug bolt pattern as the Spit? What is the capital of North
Dakota?...sorry have I been running on?
Thanks in advance
Any and all comments/suggestions are welcome