Tire pressure

I have Continental HCS 14 R20 tires on our Saurer 6dm. The PSI rating on the sidewall is 120 psi. The tires currently have 95 psi in them since I bought the truck. The treadwear is not good. The center tread is wearing out faster than the outer tread. Under inflated tires, it’s usually the opposite. What is wrong here? Thanks!



Expedition Leader
120 PSI is the maximum pressure for maximum load. You need your load, by axle and the inflation chart for your tire. FWIW - My 917 at about 18,000 lb. runs in the neighborhood o 50-60 PSI and the wear is even. But run the numbers for yourself.
You are lucky you’re overinflated rather than under. Under inflated tires that big tend to explode long before they wear out. Weigh each axle separately. I suspect 60 psi will be enough for the front, 95 for the rear.
I have often wondered how much increase in pressure is applied when going to altitude. If we are at 5 bar at sea level , how much at 5000m. Would people be adjusting their pressures as the ascend and decend. I dont but sometimes think i should



Expedition Leader

When I lived at altitude, I would not bother to adjust for brief descents, and vice versa.

So when I lived in Guayaquil and drove to La Paz for about six weeks and did nothing. In any case, we often went up and down each day and over pressure is safer than under.

In your case, depends on how long you will stay up or down - more than a week or so I would adjust at sea level and altitude. Just grab your gauge and set appropriately for weight. Probably more important to adjust pressure when you descent than ascend.
You might have to play with chalk or printing your tyres.
It was a lot of trial and error to get my Unimog tyres pattern looking good.

Btw, Cool truck. Extreme heavyduty,
One might think its a quarry truck just to look at its framerails and axels !
I put a line of chalk across the tire, drive down the street and see what part wore, I readjust the pressure until the entire line is gone within ruffly the same driving distance each time.... I hope that makes sense, lol it does to me at least.