Problem solved. Thanks.

 

What does the door jamb sticker say? What is the maximum pressure stamped on the sidewall? Are these P-metric or LT tires?

 

35 psi, but that's a 275/65/18

 

Nitto doesn't have any psi info on their site that I can find, and I highly doubt the same psi for a 275/65/18 is the same for a larger 305/60/18 tire.

 

Should be on the side of the tire.

 

If the door jamb says 35, run 35.

 

Going to be swapping back to stock tire size in a few days anyhow, these Nittos are badly cupped.

 

Boy did that help! Replaced the worn/cupped Nittos with Michelin LTX AT/2. Went back to stock size. Handles and,drives so much better, quieter, and no hopping now.

 

If I was to run the recommended door jam pressure on my truck I wouldn't have gotten 10,000 miles out of the rears. Front recommended 55 rear is 60. You should set your tire pressure according to how you drive and the climate you are in. I.E. if you are hauling half payload a few pounds under. Daily driver more than a few pounds under. Mic them every 5 or 10000 miles to track wear.

 

Stock size according to door jam sticker is 35 psi. Running a few psi higher right now. Biggest load is towing a boat once or twice a week.

 

You never did say whether the tires are P-metric or LT and what the max pressure is stamped on the sidewall, even though I asked, this makes a difference. P-metrics should be run at door jamb pressures. LT's are different, depending on load range.

 

The old tires were Nitto Terra Grapplers, 305/60/18.

Sticker on door jam is for stock sized 275/65/18.

Seeing as I threw the old Terra Grapplers away, I"m not overly concerned with the pressure in them at this point.