Bigger Tires = New Tunes?

[Jackpine]

Originally Posted by KIRT

Thanks Jack....I do think it is talking about changing the actual gears....like I said it was kinda vague

Great! If you've ever had to write a "user manual", you'd soon know how difficult it is to mean what you say to everyone. Larger tires effectively reduce your Gear Ratio. Smaller tires do the opposite.

The Tire Size (TS) and Gear Ratio (GR) settings in the Gryphons are there to make the speedo and odometer read correctly, and to make the transmission shift at the proper points in normal, part throttle shifts. The settings DO NOT restore any "loss of power" you get by upping the TS (reducing the GR). The custom tunes CAN help, but only to a point. I've got other posts in the forum that talk about the effect of increasing tire diameter.

Essentially, a 1 inch increase in tire diameter in the 32-33 inch range is going to cost you about 4% in perceived power. A 2 inch increase costs about 9%. You can really only get that back by changing axle gearing.

- Jack