I am increasing my 2011 5.0 Scab tires from 275/65/18 to 275/70/18.

I am wondering about tire pressures, they are E rated 10-ply tires (Cooper Discoverer XLTs) I'm assuming the specs on the door are for regular road tires.

I do a bit of towing, but wondering what pressures should be to keep those tires healthy in the long run.

Thanks for any info!

 

80's your max, as you likely know already - as for cruising around unloaded, you're likely better down in the low 40's i think.

There is an article somewhere that actually goes into the maths behind what pressures you need when towing with the charts for actual calculated loads and pressures.

 

Then 80 PSI number on the tire is for heavy duty trucks with 10,000 lb+ GVWR. The Wheels on 1/2 ton trucks aren't designed to stay together with 80 PSI in them. Even guys driving 3/4 and 1 ton trucks with 7000 lb curb weights only run 50-55 PSI unloaded and air up to 80 when loaded heavy.

The PSI printed on the door sticker is a good place to start. You may find a little less is needed for a good ride. No more than 50-55 is needed when hauling heavy.

 

Chalk test will reveal how much psi you need, to be safe I bump mine up a bit for long over the highway road trips but for normal running around the chalk test will be your best bet to determine psi.