tire pressure

[marty christensen]

I am confused about proper tire pressure.  I used inflate my tires to the factory specs as shown on the label by the drivers seat.  The specs call for 115 psi for the front tires, 85 psi for the drive tires and 80 psi for the tag.  I recently had some work done on the coach at a shop that sells tires and his comments were the tires are made to be inflated to max pressure for proper wear.  So he filled them up to 125 psi and I have running on that pressure for a while.  The coach now rides like a cement truck and driving on all these great roads in Il, In, and Mi I even lost a hub cap.  My tire size is 80x295 for all tires.  The tires are the original Goodyear tires from the factory.  What do some you use for tire pressures?

Marty Christensen
08 Contessa  C9 400hp

[Stan Simpson]

Marty,

Tire pressure is dictated by the weight on each axle, preferably each corner. If you go to a big FMCA rally, they usually have an outfit there that can weigh each corner of the coach separately. Without that option, you can go to any CAT scale at a truck stop and weigh the coach yourself, to at least get what's on each axle. When you pull in, if the scale is empty, just pull up on it. Then go in to the fuel desk, and they will weigh you and give you a printout. Cost, around $9.

Then, once you know the weight of each axle, go to the website for your tire manufacturer. Look up your tires and weight on each axle. The chart will tell you what psi to have them set. I generally run about 5 psi higher than the chart, because I couldn't get in to get weighed at the last FMCA I attended, so I don't know the exact weight of each corner.

The maximum tire pressure is shown on the sidewall of each tire.

You should see a marked improvement over your ride! Good luck!

Stan

[Joel Ashley]

Maximum pressure is for when you are loaded to the max.  If you aren't up to your GVWR, reduce pressures to match your actual load, as per the heaviest load on one side of each axle.  125psi is fairly high.  I'd guess your original 115/85 is a better fit.  But as Stan mentions, you need a fully loaded weight on each "corner" to be very accurate.  Consult the RVSEF website to see if there is an opportunity available to you to get reliable corner weights.  http://rvsafety.com/weighing-schedule/

High pressures may elicit minimally better fuel mileage, but the rougher ride, tire center wear, and loosened components and cabinetry counter that advantage.

Joel

[marty christensen]

Thanks, guys
I am going to go back to the factory recomendations until I can get the coach weighed.

Marty Christensen
08 Contessa, 400

[Edward Buker]

Marty,

Hopefully the factory had air pressure readings for the tires that are now on the coach. You might want to add 5lbs to each wheel position until you can get the coach weighed. That will not add that much extra weight capacity but it will also not make you ride like a cement truck.

Later Ed