Tire pressure - Diesel Forum

Chipster_27 · 03-06-2005, 12:56 PM

OK, I have to admit, I feel a little "mentally challanged" [img]/ubbthreads/images/graemlins/crazy.gif[/img] asking this one, but here goes!

I just purchased new tires for my truck. The tire pressure on the sidewall says the max load is 3000 lbs @ 50 PSI. Should I always run the tires at 50 PSI? The shop that installed them aired them up to 32 and they look a little soft.

Yea I know, stupid question, but I race go-karts with tires that can be aired up to 50 and we run them about 15 so now I have this doubt in my mind.

Oh FWIW, when I'm pulling my toy hauler I will be airing them up to 50, but for daily driving should I keep them about 32?

Man do I feel ignorant! [img]/ubbthreads/images/graemlins/eek.gif[/img] [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

Wayne B · 03-06-2005, 01:05 PM

You didn't give any real info. What size and Load rating. What vehicle Pick Up or an Excursion. It makes a difference.

First it sounds to me like they didn't put the correct load range on. Your suppose to have load range "E" which has an 80 PSI Max PSI not 50 Max PSI. The weight rating is just under what the Excursion came with. I would go back and ask why they didn't match the load and weight rating that was on the truck.

Wayne B

GrampyJim · 03-06-2005, 01:14 PM

I'll agree with Wayne.... Your VIN label (if the truck is new enough) or the tire spec label will likley have your recommended pressures at 55 front and 70 rear (Jeez.. I do this all the time and I still can't remember).

The numbers on the side of the tire only indicate the load bearing capacity of the tire and can have little to do with what the chassis manufacturer recommends.

ozhoo · 03-06-2005, 02:01 PM

Goodyear publishes a handy dandy load/speed/pressure table.

O

**SmokeyWren** · 03-06-2005, 08:25 PM

[ QUOTE ]
Oh FWIW, when I'm pulling my toy hauler I will be airing them up to 50, but for daily driving should I keep them about 32?

[/ QUOTE ]

Use that Goodyear chart and do what it says. It probably says 40 or 45 front and 30 or 35 rear unloaded. And 45 or 50 front and 50 rear when loaded for bear.

Of course, that means your first chore is to go weigh the truck when it's full of fuel and with the normal stuff and passenger(s) you haul when you're "empty".

Then weigh it again when you're loaded for bear.

And "weigh" means to go to a truckstop with a CAT scale or a J scale and get the axle weights - not just the total weight. Divide the axle weights by 2, and then use the next higher weight on the chart to find the correct PSI.

For long-distance high-speed interstate driving, you can safely put 10 PSI more in each tire than the chart shows. But don't go over 50 PSI unless the tires are "LT" tires.

If you have an axle that weighs more than 6,000 pounds, your truck is overloaded and your tires are now a danger to you and yours. [img]/ubbthreads/images/graemlins/frown.gif[/img]