“Those suspension guages aren’t accurate”

My tractor gauge is usually 62 which is max, I do know that,,what the trailer axles weigh is anybodies guess.

 

I have a daycab kw with 7000 and I'm 35,000.

 

JetA is 6.6 pounds per gallon at 72 degrees. At 80+ degrees it gets a little lighter (not much). I haul 8500 gallons all the time and cross several scales, never been pulled in.
Even hauling AvGas with a four compartment trailer I sometimes haul 8500 but most AvGas loads are 8000 gallons. The tractor weighs only 13,000 with a full tank.

 

And then tandem vs tridem. I used to carry a cheat sheet/spreadsheet (on my phone).

 

My front end alone weighs 11ish.

13+ loaded.

 

Actually the tractor weighs 15200. I don’t know how I got 13000.

 

Ok, so here's how wildly inaccurate these gauges can be. I just got back from a trip to Cavalier, ND. On Weds. morning, I ran over to the rail to pick up a container, said to have a cargo weight of 42,000 lbs +/-. Got it checked out, suspension gauge, with full tanks, read 62/63 psi, took it over to the scale, axled it at 34,360 on the drives, 30K on the tandem. Took it to our yard, boss and I gave the chassis a critical once over, decided it wasn't safe for the 2,200 mile round trip, we transloaded it to our 53' trailer. Once loaded, and on level ground, suspension gauge was under 60psi, tandems were all the way up, 40 pallets, 16 doubles on the nose, single stacks, then 4 rows of triples on the tail. Slid the tandems back 7 holes, knowing I wouldn't hit an open scale of consequence until N. Dakota, I ran with it. Thursday morning, 1/2 tanks, decided to scale it before I left Mitchell, SD, according to that scale, my suspension gauge sitting a hair over 60psi, I was 33,360 on the drives and 31,300 on the tandems. Filled up at Fargo, should have scaled it, but my gauge was now at about 64 psi.