Front/Rear Tyre Pressure when Loaded

Joined
May 22, 2015
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I have a 80 Series with full time 4WD. I try to keep my tyre pressure even at all 4 as best as I can to reduce drive line wear.

When fully loaded (off roading), I the rear half of the car sitting lower then the front, due to the weight in the back. This can be leveled by having more PSI in the rear tyres compared to the front. Additionally, at times I travel on on-road to get to and from locations, fuel up, etc., and I'd like to avoid airing up to full road pressures during these short periods (distances of ~50kms on-road driving).

Will driving on on-road with mixed tyre pressures result in wear to the drive in this situation? I image when fully load, and with the rear sitting lower then the front, there rolling diameter of the tyres would be different anyway, and could having higher pressure in the rear possibility reduce drive line wear?
 
Joined
Nov 9, 2012
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11,565
Location
Olathe, KS, USA
I have a 80 Series with full time 4WD. I try to keep my tyre pressure even at all 4 as best as I can to reduce drive line wear.

When fully loaded (off roading), I the rear half of the car sitting lower then the front, due to the weight in the back. This can be leveled by having more PSI in the rear tyres compared to the front. Additionally, at times I travel on on-road to get to and from locations, fuel up, etc., and I'd like to avoid airing up to full road pressures during these short periods (distances of ~50kms on-road driving).

Will driving on on-road with mixed tyre pressures result in wear to the drive in this situation? I image when fully load, and with the rear sitting lower then the front, there rolling diameter of the tyres would be different anyway, and could having higher pressure in the rear possibility reduce drive line wear?
Each AXLE should have the same tire pressures on them. Rear will have the same on both sides and front will have the same both sides.

Do NOT try to correct ride hight with tire pressures. They are "unrelated".

Tire pressures can be adjusted to properly carry the load.

What you are referring to is the "rolling radius" of the tire. Yes, it is appropriate to adjust tire pressures on a Full Time 4WD truck to achieve equal rolling radius (RR) on front and rear to get "neutral" drive line interference from the front axle vs rear axle. Some will say this does not make a difference, but I can tell you from many years of doing this it can absolutely make a difference.

1) Do NOT exceed the maximum rated pressure on your tires, regardless of load.
2) Do NOT exceed the per tire maximum load of the tires.
3) Do NOT exceed your GVWR of the vehicle when loaded and any trailers.
4) Keep the tire pressures equal across each axle.
5) you can adjust the front and rear tire pressures to achieve the best driveability while loaded.

The rating and pressure capability of tires varies widely by brand, type and design of the tires.
I choose to run Goodyear Duratrac 285/75-16 in and E rated version. The E-rating gives a heavier sidewall than a D-rating and I can carry a heavier load per tire. I chose this because I constantly carry 600-800 LB of tools and equipment in my truck. However, I still choose to run equal pressures in the front and rear because the tires can handle the extra load.

If you want to correct your RIDE HEIGHT for better handling, I suggest heavier springs, or use of air bags inside the springs on the rear. I have the OME "heavy" springs on my truck and I also have air bags in the rear because I frequently have a wheelchair lift and a 400 LB power wheelchair in the back of my truck. This really makes it squirrelly on the road unless I put pressure in the airbags to level the truck. Otherwise, I get a bad "tail wagging the dog" effect.

If I am pulling a trailer, then I will run 45 PSI in the rear, and 35 PSI in the front to stabilize the rear of the truck as well as correcting a little of the RR.

These trucks have a center differential and this is designed to take up variances in speeds from the front axle to rear axle due to tire variances and tire pressure variances. It will be minimal wear, but it does occur. If you have a 93 or newer and depending on location, you may have a viscous coupler in the transfer case that helps reduce drive line clunk and slop. A variance in RR will place a slight amount of wear on the VC as well.

Please add your location to your avatar as well as the truck make, model and year to your signature line so we can all know what you have without having to ask every time.
 
Joined
Nov 9, 2012
Messages
11,565
Location
Olathe, KS, USA
Apparently there are some people I come across that go by the maximum tire pressure printed on the side wall. 🤦‍♂️
Yes. I think they need a good dentist too. The rating on my Duratracs is 85 PSI. Driving with them that tight makes them squirrelly in the rain and will knock your teeth out with the smallest bumps.

There are afew that delve into the deepest depths of tire pressures and stating the you should NEVER run under 35 PSI.

It's primarily about the contact patch of the tire with the road, and not running them under inflated to generate heat and flexing that will cause failure. You can run higher pressures depending on weight, but the contact patch where the rubber meets the road is very important for proper braking and handling.
 

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