Tire chalk test

[SZR48207]

I'm running the factory tire size for my truck, although a different make/model tire. Door jamb says

Front: 29 psi
Rear: 32 psi

Drives fine and tread wears evenly, but feels mushy and "heavy".

I did the chalk test at 34psi all around and as far as I could tell, the tread was still evenly applied to the road surface.

For the rears, no biggie since it's +2psi, but this means the fronts are +5psi from the mfr recommended setting. Seems a bit odd?

Although, to be fair, I did add an off-road push bar to the front bumper and sliders/steps for the cab. Around 250lb of added weight over factory. Would this factor in?

 

[ripcord]

Not sure about your specific vehicle, but if you run higher pressures, you still might consider going a few pounds higher in the back than the back. The reason they specify different pressures front to back is to balance traction when cornering. Higher pressures in the back is normally used for vehicles that get loose in the back first.

 

[SZR48207]

Not sure about your specific vehicle, but if you run higher pressures, you still might consider going a few pounds higher in the back than the back. The reason they specify different pressures front to back is to balance traction when cornering. Higher pressures in the back is normally used for vehicles that get loose in the back first.

That is really good to know! I can go with F:32/R:34 then.

 

[Mainia]

The tire pressure on the door pillar is for use for grandpa and grandma who are going 40 mph on the hwy and 20 mph in town. (Sarcasm) Good luck having meaningful/somewhat safe accident avoidance with those sub-standard inflation values. The minimum value I use on my family’s cars are 34 cold. My personal car, a Hyundai Kona AWD with heavy Sport driving, is 37 cold. Which means 40-41 hot. I have even tire wear on all three of our cars listed in my signature below. Some cars and cuv/suv’s have weird flakey/handling characteristics with door piler tire pressures that let the tire’s sidewall roll over and some get tire pogoing/bounce in an emergency maneuver, these can are lessened with increased tire pressure. I just never could see why engineers went so low with these tire pressures when clearly a couple more psi helps out car handling without any more tire wear. I guess a smoother ride trumps safety.

 

[Pew]

Higher pressures in the back is normally used for vehicles that get loose in the back first.

Although I would believe in the case of a truck, the rears would be higher than the front to compensate for loads carried in the rear.

I find it odd that older trucks tend to have really low tire pressure recommendations from the factory.

 

[CapriRacer]

The chalk test is unreliable. Here's why:

This is the footprint of the same tire at different loads and inflation pressures. No matter what inflation pressure you use, you'll get the same answer using the chalk test.

Then there is this one:

No matter what inflation pressure you use, the answer will be that you need less pressure.

All of that is because the shape of the tread surface is only slightly correlated to inflation pressure, but it is mostly controlled by the the things the tire engineer designs into it. Sometimes flat is NOT what the tire engineer wants.

 

[Traction]

CR nailed it. Everyone wants to out think the engineers. The tire is the other half of the spring in your suspension.
If you could only look inside a tire?