Do i need to adjust tire size up or down?

[jac04]

If the actual elapsed distance is greater than what’s recorded by your dash, you need to recalibrate to a smaller tire size with your tuner. I.e. 34.4” instead of 35.0”.

Actually, it's the other way around for this scenario. You need to tell the vehicle that it will cover more distance for the same number of revolutions, meaning you need to program the vehicle with a larger tire diameter.

Sponsored

 

[ShadowsPapa]

Actually, it's the other way around for this scenario. You need to tell the vehicle that it will cover more distance for the same number of revolutions, meaning you need to program the vehicle with a larger tire diameter.

Good catch. It figures distance traveled per revolution. Bigger tires cover more distance per rev.
It's off roughly 4%

 

[Rusty PW]

I'd have taken MTs off well before only 1/16" of thread remains - they'd be closer to racing slicks, and worthless in mud. They'd be at the recycler's.

Your example is full off the truck diameter. So although there's a fair amount off the diameter - gotta give ya that - the rolling circumference loss would be a bit less, and your truck would only sit about 5/8" lower than when new.
But then - That's enough to see - how can you stand your truck dropping that much?

OK, I'd probably shoot for the middle of the road on tires that lose that much - that way over the life of the tire, it would average out. Program in smaller than a new circumference, but larger than a worn circumference. And if your wife gripes about things being off, tell her you need to drive the truck more to make it accurate. Then when they are worn, you have an excuse to replace them sooner.



The tire maker's diameter is not what the truck sees and shouldn't be used is my point.
It's not even a good starting point.
The guys using a tape measure on an installed tire measuring from the ground up are going to be closer. Check all the posts from guys who used the tire chart numbers and then came asking "what should I do" because it was so off.

The tire charts are also max PSI, not what you'd run on your own truck.

The tire pressure you use on your truck, and your truck's weight affect the rolling circumference. If in doubt, check out how ITPMS works and how much impact tire pressure has on the rolling diameter or circumference.

I posted that to see what your reply would be. LOL I knew you would reply. LOL I was hoping a few others would bite too. LOL

 

[Rusty PW]

These are some incredibly light weight tires!!!!

They're for 20" rims. So there is no side wall.

 

[mrmo]

See the link below. The speed rating 121Q. For some reason, I can’t scroll any farther to the right on my phone (reference the table below). There should be a column with actual diameter if you keep going to the right.

https://www.fueloffroad.com/gripper-tires/truck/

One thing for sure, those tires are LIGHT, 35lbs for a 35 x 12.5??

 

[CrazyCooter]

One thing for sure, those tires are LIGHT, 35lbs for a 35 x 12.5??

I bet the specs are wrong and that in kg's

 

[Oak]

I just did a trip and went from 38s to 37s reset the tazer with the ew measurement average.

My milage went down and when my GPS Said I was doing 65 my speedo would be 66 or 67.

Which way should I adjust my tire setting.

Can't believe my mpgs would drop going from 38x13 milestare Mt to 37x23 ridge grappler with less sever tread.

 

[CrazyCooter]

I just dud a trip and went from 38s to 37s reset the tazer with the ew measurement average.

My milage went down and when my GPS Said I was doing 65 my speedo would be 66 or 67.

Which way should I adjust my tire setting.

Can't believe my mpgs would drop going from 38x13 milestare Mt to 37x23 ridge grappler with less sever tread.

You are probably right on. Usually the speedometer will read 1-2+ when the odometer is perfect.

 

[Escape.idiocracy]

I just dud a trip and went from 38s to 37s reset the tazer with the ew measurement average.

My milage went down and when my GPS Said I was doing 65 my speedo would be 66 or 67.

Which way should I adjust my tire setting.

Can't believe my mpgs would drop going from 38x13 milestare Mt to 37x23 ridge grappler with less sever tread.

This probably has a lot to do with weight…. I didn’t look it up- but I bet the milestars are 10-12# lighter per corner…

 

[Oak]

This probably has a lot to do with weight…. I didn’t look it up- but I bet the milestars are 10-12# lighter per corner…

I didn't think about weight...but they are heavy lol

 

[Orange01z28]

To drive you OCD types crazy. New 35" MT tire with 21/32" of tread. You take them off at 2/32" of thread remaining. Does it still have the same OD as new? You lost around 1 3/8" in height. Think your speedometer and your odometer still correct from when you reset it when you first got your tires?

I put on nearly 45k miles after the shop I got my first set of tires done at set the computer to 36" for 35s. Add the wear equation in and who knows how many extra miles are on my odometer

 

[dslfreak]

I bet the specs are wrong and that in kg's

It is a Canadian jeep

 

[dslfreak]

I just started it from 33.95 to 34.13 (up 2 notches) see how it looks

 

[XraytecH]

Curious...

Did you set the tire size stated on the tire or did you measure the tire?

 

[dslfreak]

Curious...

Did you set the tire size stated on the tire or did you measure the tire?

Measured 1 tire with level and tape measure

Sponsored