Hit-by-thunder, your scientific math will be a good topic at the coffee shop. Should get a rise out of some of "over the hill guys", thanks for the formula. Every one needs to remember to have the truck weighed by axle, need actual weights not posted max weights.

 

What if your truck is really light and you use the stronger 10ply tires. Could this equation still be used?

 

Bill, you nailed it, You HAVE to have the truck weighed by axle. If not just use the "good enough" formula on the door VIN placard

yes the even if you run Load Range E (10 ply old school). with in reason though. If you a running a 10 ply on a ranger then like 10 psi is not good <---rough numbers btw

I used to hate customers coming in saying the vehicle rides like a buck-board. Only to check the tires with 50 psi in a maxed 35psi tire. "but the tire looks flat" when you put 32psi air in it

Rob/HBT

 

I've always kept 35 in me and my dads 265's... as well as my moms 215's.

 

The equation gives me 28 psi. I called my tire manufacture's tech. support and they recommended that I don't run them below 50 psi. They didn't really explain other then saying because they're load range E. I'm currently running them at 56 psi all around which is 70% of 80 psi. I figured 70% of max would be good. My f150 rides nice at 56 psi, not rough at all as many would think. It's not the squish 35 psi ride I had before but I'm getting better acceleration and gas mileage now.

 

I just got my tires rotated yesterday and they said that they set all 4 tires at 40 psi I think I am going to bring them up to 56 or so also being that they are E load range toyo mt.

 

Ya Ratatat, that is where when you have 10 ply on something really light (rear of an F150) that hauls nothing. Like I said with my dually I ran 28 psi in my duals with a max at 80 psi. Boss told me I was nuts to run that low. Told him, do the math it all works out and the tires wore forever. The little nubs wore off nice and even accross the face of the tire. Never showed signs of under inflation in the tread wear at all. Look at tires in a parking lot when you stop at a mall so many of them are over inflated then before you know it they are wore out on the center, time for new ones,....again

This is the formula I use, it makes sense and it works for me is all I can say

We took a course on tractor tire ballasting, air pressure and power hop on the big 4WD's, I experienced it too. In a nut shell, think of a basketball on concrete which one bounces higher, "more rebound" the one with little air or the one with more air,............see.

 

I will be trying this out. I stopped by a scale after work today. My truck weighs a total of 4,600lbs. The steering axle weighs 2,660lbs and the drive axle weighs 1940lbs. Tires read 3042lbs @80psi. That gives me 35psi for the front and 26psi for the back. I'm I right?

 

yes, you got it right ratatat. 34.97 and 25.5 psi.

With that pressure the tires will wear evenly, now remember when you add a load, bump them up. Heat maybe an issue running at 26 psi Run them down the hiway for awhile and feel the tires. Compare the fronts to the backs to see if the heat level is the same. Heat is what kills a tire. Flexing the side wall at hiway speeds heats a tire but it is pressured correctly and not stressed. It is better to run 26 psi empty than a heavy load with 80 psi.

Rob/HBT

 

This site just amazes me. I learn something every day. thanks everyone