After fitting the new rims speedo accuracy has proved to be an issue.
When I bought the truck it had the 20’s fitted as opposed to the standard 16’s and I noticed the Jet SCU2000 fitted to adjust for the rim change effect on the speedo and no doubt remove the top speed limitation.

Jet Performance Products is a proven leader in automotive tuning technology. Their background in tuning started with Jones Performance Fuel Systems over 40 years ago. The Fuel Systems Division has given Jet the opportunity to tune everything from NHRA drag race cars, to off-road race trucks and Sprint Cup cars. This experience has been the basis for the Jet line of performance tuning products for street applications. JET’s engineering staff is unsurpassed and considered to be the best tuners in the industry.
Constant changes in computer technology of today’s cars and trucks demand that the JET engineering staff be the best. Automotive computer systems progress daily, just like every form of technology. The folks at Jet Performance Products are dedicated to providing you with the latest in performance tuning technology possible. Extensive research and development, dyno testing and constant fine tuning ensures the most power from each part they make.
I’ve now got to RTFM to see how to set things for the new rim configuration, watch this space!
Hang on, blokes aren’t supposed to read the manuals, where’s the fun in that. 😀