Tire Pressure & air compressor.

[Chaz]

Hey Guys,
  I'm getting ready to hit the road for a short trip this afternoon to INdy for a car show and was doing my maintenance check. I was reading my tire pressures on the tires and found everything from 95# to 130# on the a tires in the positions they are in. (Front/single , rear/duel) Looks like I have a few different kinds of tires.   
  Unfortunately, my studio compressor doesn't get much, if any, over 90#. Can the bus compressor get that high? If so, where would you take it off from? Or is there any difference where I would put the hose?
  I may have to stop by the truck stop or something otherwise.
  Thanx!! I got get back to checking and packing.
    Chaz

  p.s. hope this makes sense. I'm "humpin and pumpin" to get done and outta here.

[tekebird]

unless you have a grossly heavy bus 90PSI is more than adequate and is probably right where they should be

[Chaz]

I thought a person was supposed to go by what the tire was rated for as opposed to "rule of thumb". (??)

[FloridaCliff]

Chaz,

You really need to know the weight on each tire/axle and then compare to recommended chart for that tire, if you want optimum air pressure for that tire.

That is for maximum tire wear/ride etc...

Of course WE will never wear out a tire, so what Teke is suggesting is a good average for best ride/wear, until you can find out those other numbers.

To me its a trade off between ride comfort and rolling resistance.......

Cliff

[Don4107]

The proper way is to weigh each axle and inflate the tires according to what the manufacture recommends for that tire at that weight.  If your compressor only makes 90 PSI, it will depend on what the cut-in pressure is.  It is hard, time consuming, to increase the tire pressure much if your tank pressure is close to the tire pressure. Worth stopping somewhere if you need to add much air unless you have more patience that I.

You can plumb in a chuck on the bus air system in the future.  If you put it in the right place you can use it both to supply air for things like tires and air tools and also use it to air up the bus with shop air.

GMs tend to be toward the lighter end of the bus world.  As Teke said, 90PSI will getting you going and will give a good ride until you find out for sure. 

Good luck on the trip
Don 4107

[kyle4501]

Tap into the bus air at the rear for maximum pressure availability. Just be sure to tie in after the check valve. If you have an air drier, tap in after it so you will get dry air for filling your tires.

If you plan on airing up your bus from shop air, I'd tie in before the air dryer in order to keep as much moisture out of the bus system as possible.

Also, it's a good idea to put a shutoff valve on the taps.

[Len Silva]

You might also want to invest a couple of dollars in a locking tire chuck.  It can take a long time holding the chuck to fill a tire.

[luvrbus]

Len, that's good advice I have one with a 3' section of hose with a regulator on the other end I hook it to a tire and the compressor set the pressure on the regulator to 105 psi go do other thing this system has worked great for me and no standing around with a tire gauge or you can use a regulator at the compressor fwiw

[H3Jim]

I finally gave up an just bought a sears pancake compressor.  The harbor frieght one was rated the same, but would not pump up the bus tires.  The sears one, rated at 150 psi does just fine.  Small enough I always leave it in the bus, so whenever, wherever I am and want to check tire pressure, I do and can add to whatever I need.

The bus air works, but not fast enough as the highest pressure is pretty close to the tire pressure.

[TomC]

Chaz- if you go by what the maximum tire pressure on the side of the tire is, you'll have a bus that rides like a fork lift-especially since we are not even close to maxing out the tire ratings.  For instance, with my 11R-24.5 16 ply tires, I could pump them up to 120psi.  But after weighing the bus with 10,500lb in front, and 20,500lb in the rear with full tanks, I could run as low as 80psi and be alright.  I run 90psi all around just to be on the safe side and the bus rides great! 
While you're on the road, find a truck stop with a scale and weigh the bus to find the individual weights of the front and rear axle.  You can look up on line as to the proper inflation for your tire size-then add 10psi to that for good measure.  You'll be surprised at the improvement in ride quality.  Good Luck, TomC