Speedometer recalculation for larger tires

[AbzDad]

I did a search and only found 1-2 posts. This year I am putting larger tires on my truck in the summer, which causes my speedometer to be off by 5 mph at 55mph. I have been looking for something that can recalculate the speedometer to be correct. I prefer something that I can easily re-program/remove when I put my stock tires back on in the winter. I know Rough Country has an in-line box (part number 90051) that changes the speedo/odometer and transmission shift points to account for the larger tires. I really don't want another electronic box in my engine bay, so hoping someone has seen another product that can program the ECU to account for larger tires. Has anyone seen/used something beside the RC box.

 

This is on a 2024 Sierra 2500.

[chris21]

The rough country inline is the only one that claims to work with Global B gm trucks. It doesn't change shift points for the transmission though. Your speedometer and odometer are probably reading 2-3% high on the stock calibration if you have 275/70/18's now, but that is only 1-1.5 mph at 50