This was difficult to obtain, and my tire dealer kept recommending running 60 psi in the rear and 50 in the front on my BFG All Terrain AT 305/65R17 tires.

I called BFG and they recommended running 55 psi all around. After two emails, two phone calls and 3 hours on the phone hearing "We don't have load charts, and we recommend running the same pressure as listed on your driver's door" political BS, I finally got a load chart!

The proper way to set your air pressure is using the manufacturer's load chart and matching the weight carried by the tire to the corresponding air pressure that will carry that weight.

If you add more weight you add more air. If you can't do this, run the highest air pressure for the weight you expect to carry.

Here's the BFG 305/65R17 Load Index Chart

Tire Size - LT305/65R17

35 psi - 2205 lbs
40 psi - 2385 lbs
45 psi - 2590 lbs
50 pis - 2835 lbs
55 psi - 2955 lbs
60 psi - 3075 lbs
65 psi - 3195 lbs

For reference, the original Michelin LTX 265/70R17 chart is:

35 -- 1890
40 -- 2075
45 -- 2255
50 -- 2470
55 -- 2595
60 -- 2760
65 -- 2910
70 -- 3005
75 -- 3100
80 -- 3195

So on my Mega Cab door placard, the recommended tire pressure for an unloaded truck is 40 psi rear, 50 psi front. This means the original tires would carry 40psi = 2075lbs on the rear, and 50psi = 2470lbs on the front.

The new BFG's should be 35psi = 2205lbs rear (the lowest recommended pressure) and 45psi = 2590lbs front.


This is a far cry from the retailer telling me to run 50 front and 60 rear, and has contributed to the faster wearing center tread area I am seeing.

So after all this, I tried 35 psi in the rear and the ride was nice, but the tires look too squishy, so I am running the rear at 40 psi, and the fronts at 48. My axles weigh in at 4600 front and 3300 rear. I will chalk the tires when the roads dry up and see what the wear pattern looks like and report back.

 

That's very interesting. Someone on this forum once proposed that the load rating and PSI was a linear relationship, which I was suspicious of. This proves that I was right in being suspicious!