Tire Size Change Question

rednoved · #1 Sun, May 24th, 2009, 12:24 PM

When we have a custom tune made for us, is OUR tire size part of that tune? If it is, can we change it if I were to go to a different size tire? I plan on lifting the truck not too far down the road. Or even if I add a leveling kit in the next month, I'll probably buy larger tires.

***Jackpine*** · #2 Sun, May 24th, 2009, 12:46 PM

Quote:

Originally Posted by rednoved

When we have a custom tune made for us, is OUR tire size part of that tune? If it is, can we change it if I were to go to a different size tire? I plan on lifting the truck not too far down the road. Or even if I add a leveling kit in the next month, I'll probably buy larger tires.

Yes to both questions. You give Bill your tire size and he programs it into the tune. If you change tires later, you can revise the size using the Custom Options menu.

- Jack

rednoved · #3 Sun, May 24th, 2009, 12:53 PM

Quote:

Originally Posted by JackandJanet

Yes to both questions. You give Bill your tire size and he programs it into the tune. If you change tires later, you can revise the size using the Custom Options menu.

- Jack

Thanks. So I wouldn't need to order another custom tune after the lift. That's good to hear!

stryker6040 · #4 Mon, May 25th, 2009, 12:18 AM

Jack the number you gave me was almost dead on. just a little more fine tuning and everything should be as close to prefect as we can get thanks a lot for the help!

***Jackpine*** · #5 Mon, May 25th, 2009, 12:50 AM

Quote:

Originally Posted by stryker6040

Jack the number you gave me was almost dead on. just a little more fine tuning and everything should be as close to prefect as we can get thanks a lot for the help!

You're most welcome! Glad we could help you out.

- Jack

Mexico Dan · #6 Sun, June 7th, 2009, 10:42 AM

I just got my custom tunes, took it out for a 250 mile drive this weekend. I don't have a gps, but using the mile markers on the freeway, my odometer flips about 150 feet before each mile marker. I also feel "slow" driving the same roads I'm used to. Decrease tire size a little? I have 285/75/16 Terra Grapplers, max psi 65, and running them about 43. Is this too low?

***Jackpine*** · #7 Sun, June 7th, 2009, 03:05 PM

Quote:

Originally Posted by Mexico Dan

I just got my custom tunes, took it out for a 250 mile drive this weekend. I don't have a gps, but using the mile markers on the freeway, my odometer flips about 150 feet before each mile marker. I also feel "slow" driving the same roads I'm used to. Decrease tire size a little? I have 285/75/16 Terra Grapplers, max psi 65, and running them about 43. Is this too low?

Your 150 feet in 5280 feet is about 2.8% in error. You COULD try subtracting 2.8% from the current circumference you are using. The pressure seems all right to me - are you using OEM sized tires and wheels? If so, there should be stickers on the truck recommending the tire pressure. However, since the max pressure is 65, I doubt you'd hurt anything using 50 psi cold.

When I enter your tire size in Bill's Gear Ratio Calculator in Pegasus and use a 7% rubber squish, I get a circumference of 2525 mm. What are you currently using?

- Jack