Speedometer recalibration with bigger wheels ?

[fazool]

I was rather enamoured with the 2005 XC70 AT concept car IPD put together a while back. It got me to thinking.

Back in my street rod days, I ran 15" wheels on my 14" chevelle. My speedo was always off.

What the standard protocol these days for correcting this issue ?

Just running a lower profile tire on larger rims would keep the outside diameters the same and solve the problem, but I mean when raising a car and using taller tires.


For example, the same profile and sidewall tires on 17" vs 16" rims results in 1.5" greater radius and a 5% increase in circumference and, therefore, a 5% mis-read on the speedo (and a corresponding torque loss and speed gain).

[JRL]

There is none
What you got is what you will have
In the old (VERY) old days, you swapped a gear in the back of the tranny