Reading a load-inflation table before you air up

Air pressure is a weight setting, not a comfort dial. Every tire maker publishes a load-inflation chart showing what one tire carries at each cold PSI, check that row before setting pressure after a size swap, because the right PSI depends on the actual weight. The max figure on the sidewall is a ceiling, not a recommendation.

The door-jamb placard is the starting point. It lists the factory size and the cold PSI behind the truck's rated weight per tire. Match that weight in the new tire's chart and read across to the PSI column. Verify the construction first: LT rows and P-metric rows come from separate charts, and a listing that hides the construction letter is worth skipping for one that shows it.

One worked example covers most cases. A placard assuming 2,300 lb per tire needs a chart row at or above 2,300; if the new set reaches it at 55 PSI, that is the floor. Towing loads the rear axle, so check the rear pair against a scale ticket - the margin depends on real tongue weight.

Cold means cold. Morning readings before driving tell the truth; warm sidewalls read high and can hide a soft tire. A 30-degree seasonal drop takes real pressure with it, so check again when the weather turns and confirm the spare while at it.

Max-sidewall pressure on an unloaded truck centers the tread wear and punishes the ride. The row covering the actual weight, plus a small towing margin, is the honest number.

The habit sharpens price comparison too. A Falken Wildpeak A/T4W and a Nitto Recon Grappler A/T in one size can want different PSI for the same placard weight, and each product page keeps size, rating, seller stock, and return terms together. More options sit in the tire and wheel department.

Before airing up: pull the placard weight, confirm the new chart row, verify the wheels and valve stems handle the PSI, and sanity-check the swap with the LT vs P-metric guide and the load range guide.