View Full Version : Tire Math - Inflation vs axle ratings

07-28-2016, 03:36 PM
Tire gurus -
I have a 2008 3500 dually. Frt GAWR = 4860lbs, 2430/ tire. RR GAWR = 8200 lbs, 2050/tire. The inflation sticker says 66lbs for the fronts, 60 for the rr.

I am running Toyo Open Country H/D Tuff Duty tires.
According to the Toyo load inflation chart -
(single) 60 psi = 2280, 65=2405, 70=2540, 75=2670, 80=2755
(dual) 60=2075, 65=2205, 70=2310, 75=2430, 80=2535

Given the above, I have run the fronts @ 70 psi. And the rears @ 60 psi. (Eases the ride when not towing and I am a bit lazy when it comes to fighting with the inside dually.)
But I read here and in other forums, and have been told more than once to inflate the rr's to 80 when towing. Why bother inflating the tires beyond the axle capacity?


07-28-2016, 03:51 PM
Looks to me that the 66 psi front and 60 psi rear is perfect. Best to go by the vehicle maker's pressure suggestions.

07-28-2016, 04:38 PM
I keep thinking back to the ford-exploder firestone tire problem and would go with the tire company.

07-28-2016, 04:40 PM
Just throwing this to the discussion. My dually has 60 psi for both front and back on the door sticker. My Uniroyals say max inflation 80 psi on the sidewall. Some don't understand what the difference between max inflation and door stick psi means. If I were to inflate my rears to 80 psi ... I'd never keep her on the road as it drives like I'm on bear grease. If I were to keep my rears inflated to 60 psi ... the center of the tire wears noticeably quicker than the outside. I run my fronts at 60 psi and the rears at 55 psi with good tread wear for both. My measured pin weight is 2340#.

07-29-2016, 02:10 AM
Inflating to maximum rated tire pressure lessens sidewall flex on the tires. The pressures on the load rating sticker are based on the OEM tires. I will always inflate to the tire manufacturers recommendation. If you have a failure, that's who you're going to deal with not the manufacturer of the truck-unless the tire is in OEM warranty.