tire pressure on tow vehicle
should I increase the rear tire pressure by 10 psi, on my truck's tires or leave at the suggested 35 psi that is shown on the sticker on the door jam?
Forum Discussion
Pumping up the air in your tires to the maximum rated psi is correct if your tires are supporting the maximum weight rating of the tire. Otherwise they will be under or over inflated based on your actual load. It's not rocket surgery but I hear "advice" that is simply wrong consistently so I guess it needs to be made simpler to understand.
I took others' advice many years ago when I first started towing. I pumped up the 4 tires on my 7K pound trailer to the "max" 80 psi as suggested. The tires at this pressure can support over 12K pounds. The trailer (a 25ft toy hauler) was all over the road. I checked and adjusted tongue weight, sway controls, torsion bars etc. but none of this was completely effective at settling down the trailer. What solved it was dropping the air pressure to an appropriate for the load 60 psi.
This toyhauler as with most is not equipped with shock absorbers and that's fine usually. However what happens with over inflated tires is the sidewall which is designed to flex and absorb some of the energy from impacts does not. This energy is transmitted directly to the springs and that transmits to the chassis with no shock absorbers to dampen these oscillations, every bump in the road is exaggerated. It can in fact upset the chassis to the point of instability which is what I experienced .
These are LT rated radial tires and after lowering the pressure a bit they had a bit of sidewall bulge which is how a properly inflated radial looks. They do not get hot to the touch under any conditions which is the true test and the only real indication if your tires are under inflated. I also tow the same trailer fully loaded at 12K pounds and when I do I run them at the 80 psi maximum as recommended on the sidewall since oh yeah, they are then supporting the maximum weight as well.
You can get away with over inflating your tires to "the max" on your truck because the shocks are able to dampen the excessive oscillations from the road and inflexible sidewalls but sometimes it's just unsafe on a trailer to run the wrong air pressure be it too low OR too high..
I took others' advice many years ago when I first started towing. I pumped up the 4 tires on my 7K pound trailer to the "max" 80 psi as suggested. The tires at this pressure can support over 12K pounds. The trailer (a 25ft toy hauler) was all over the road. I checked and adjusted tongue weight, sway controls, torsion bars etc. but none of this was completely effective at settling down the trailer. What solved it was dropping the air pressure to an appropriate for the load 60 psi.
This toyhauler as with most is not equipped with shock absorbers and that's fine usually. However what happens with over inflated tires is the sidewall which is designed to flex and absorb some of the energy from impacts does not. This energy is transmitted directly to the springs and that transmits to the chassis with no shock absorbers to dampen these oscillations, every bump in the road is exaggerated. It can in fact upset the chassis to the point of instability which is what I experienced .
These are LT rated radial tires and after lowering the pressure a bit they had a bit of sidewall bulge which is how a properly inflated radial looks. They do not get hot to the touch under any conditions which is the true test and the only real indication if your tires are under inflated. I also tow the same trailer fully loaded at 12K pounds and when I do I run them at the 80 psi maximum as recommended on the sidewall since oh yeah, they are then supporting the maximum weight as well.
You can get away with over inflating your tires to "the max" on your truck because the shocks are able to dampen the excessive oscillations from the road and inflexible sidewalls but sometimes it's just unsafe on a trailer to run the wrong air pressure be it too low OR too high..
