To my surprise an email to the state department of transportation requesting a source for individual wheel weights resulted in a phone call from a highway patrol officer in the commercial weight enforcement division offering to do the weights. He apologized for not coming by the house to do them and asked if we'd be willing to meet him at a county park near their station.
Happy to oblige hooked up the toad and drove the 15 minutes to meet him. I filled the fuel and water tank but grey and black were empty. We're about 50% loaded for our 7 month cross country trip so these weights are probably off by some amount. Here's what we got (FT max weights in parenthesis):
Front Driver - 5000 lbs
Front Passenger - 4900 lbs
Total front axle - 9900 lbs (12,000)
Rear Driver - 8900
Rear Passenger - 8900
Total rear Axle - 17,800 (19,000)
Total Weight - 27,700 (31,000)
Jeep (no passengers of gear)
Front Driver - 1100
Front Passenger - 1150
Rear Driver - 1150
Rear Passenger - 1250
Total Jeep 4650
Combined 32,350 (41,000)
Wow! There is a nice operation. ^.^d Oregon and Washington State leave their scales on when their gone, a easy spot check!
34' seem to be heavy in the rear. My numbers were about the same a few years ago (only did axle weights, not corner weights).
Based on individual weights posted above I found the attached Goodyear truck load/inflation tables for our 295 75/22.5 Goodyear tires (top line of chart). If I'm reading this chart properly it appears the front tires would need somewhere between 80 and 85 pounds. The rears, I assume, divide the individual weight by 2 to get the proper information for each of the dual tires so 8900 pounds would mean 4450 per tire and 80PSI?
You're about 1000 above my weights for both ends and yes the tire pressure charts call for 85 or less on both ends.
With the LR H @ 295/75 .
S is single weight for one tire
D is dual weight for two tires together, lower.
Until I bought Brett's coach and learned about having the coach weighed, I trusted tire outlets to know what PSI I needed., WRONG!
Everyone of them always said, "100 pounds". Anytime anyone says that to you, they are wanting your money and wanting you out of the shop ASAP! :facepalm:
Anyone who KNOWS what tire pressure to use in your coach tires without asking the wheel position/axle weights is either CLAIRVOYANT OR AN IDIOT. Guess which is more likely!
Missed you, Brett.
Glad youre back.
When dealing with tire pressure / weight carrying charts, we add additional air pressure to compensate for side winds, hard cornering, air loss, cold mornings, higher altitudes and for just an all-around safety factor. Too low means higher heat which can lead to problems.
I add 5psi per tire over manufacturer's inflation tables to compensate for all the above.
All of the above relies on tire gauge accuracy.
I have tire pressure temp and pressure metal valve stem cap sending unit on every wheel on one of our cars.
The set pressure is 33 psi cold. 20 mile drive it's 36 on all wheels.
My guru buddy will only install the bendix truckers tire pressure units on his jobs. $2k plus. Plus dismounting the tires from the rims.
It also sends the temps also as he feels one without the other is useless.
Thanks for comments. Have bumped up my PSI to reflect additional load and "safety margin".
Informative FMCA on the subject below. Reinforces everything discussed here.
A Little Confused Over G vs H Rated Tires And Load/Inflation Data -- Updated... (http://community.fmca.com/topic/3692-a-little-confused-over-g-vs-h-rated-tires-and-loadinflation-data-updated-at-end/)
Based on weights and comments here's our final data:
Final RV tire pressure w/ Weight and 5 PSI Margin
Front 95
Rear. 90
As Measured without driver/passenger, full water/fuel and empty grey/black, and most gear w/o food or clothing.
Front 5000/side = 82.5 PSI
Rear 8900/side (4450/tire) = 78.5 PSI.
Add 500 per tire or 1000 per axle plus 5 PSI margin
Front - 5500/side = 91 PSI plus 5 = 96 PSI
Rear - 9400/side (4700/tire) = 83 PSI plus 5 = 88 PSI
Here is the Michelin Chart for RV's
https://www.michelinrvtires.com/assets/pdf/load-and-inflation-rv.pdf
I keep it simple and run 100 all the way around.
Good chart, if everyone gets their coach weighed on all four corners. On our XRV 255/80R 22.5 / load range 'G', we run 85 psi in the front and 80 back. That is with a 50% load of all fluids. The fronts weigh out @ 8,600, the duals are 15,000 total. As mentioned, adding some extra psi is not a bad idea if you full-time and (especially if the DW collects rocks). ^.^d
Overinflated runs on the center of the tires tread. Hydroplanes easier. Some steering wander