Tire pressure questions

Asked in another thread but can't find much on this so figured it was worth a separate thread.

Door tag on my 00 4.7 AC 4WD shows 26/35psi for front and rear tire pressures. Also just replaced my stock 16s with a set of factory 17s from an 05/06 model. Advice given was if unloaded to go higher in the front (35-40) and lower in the rear (25-30).

While I can understand changing the pressures to account for a heavy load or towing, I'm not sure why they'd of not accounted for that on the door tag unless I'm missing something.

 

Have you tried the chalk test?

https://www.tundras.com/threads/tire-pressure-chalk-test-how-to-guide.2114/#post-31099

 

Hadn't but this seems like a great idea for what pressure to run daily/unloaded

 

This will get you in the ballpark, very useful when moving away from stock tires or changing tire load ratings

 

Thanks, won't let me start any smaller than a 17inch wheel though

 

Yes it will, it is a drop down box. What was the factory tire size the truck came with and what are you running now?

 

Ah ok but now I'm not able to match the pressure. The rearsh show 35 on the tag and the calculator shows they should stay the same. But for the fronts the tag shows should be 26 and the drop down doesn't go that low (35 is the lowest).

 

What was the stock size and load rating and what size and load rating are you running now?

 

Old tires : 245/70/16 "Extra Load" Continental Cross Contact
New tires : P255/75/17 113S "M&S" Firestone Destination A/T

 

Your new tires have higher capacity (larger, stronger tire) but it states to run them at same pressure at lest- no lower than 26 lowest pressure. So, pressure listed on the door would be fine. I generally find that running a few LBs higher (just a few, a couple of pounds adjustment makes a big difference) offers better tire wear and drivability.

And Tundra2 mentioned the chalk test, easy to do and helpful. Try a few lbs higher than the sticker and see how the truck drives and tires wear, and do a chalk test to see if you are getting a good contact patch with that pressure. Here is how
https://www.youtube.com/watch?v=MIvbFgrH0IQ

 

Appreciate all the advice and it's been raining here for like 27 hours so the chalk will have to wait for a dry day but I set them a few higher than the sticker just cause it seemed low to me so we'll see how it goes when I take it out again (only drive it like once a week maybe)

 

To confirm though, when I'm towing or loading the bed heavy I should flip the 26-28 up front with the 35-38 on the rear?