I just notices a 45ft grey hound with the tyre pressures labelled above each tyre.
Front tyres 120 lbs cold
Drive tyres 105 lbs cold
Tag Tyres 95 lbs cold.
Is this only for a 45 ft coach or should my MCI 9 be set the same?
John
John,
It surprises me that the front is more than the rear, especially since the engine is in the rear.
I don't remember reading anywhere in the Driver's Manual for my 4104 about tire pressures?
However, I would assume that since our buses are not filled with passengers that the front should be no more than the rear and maybe even less for better riding comfort.
Also Gus your 04 was built before radials, so the pressures would not apply.>>>Dan
I have always been told to weigh each axle and look up those weights on the tire manufacturer's web site to find proper inflation for your model tire. Jack
Don't inflate your tires based on what Greyhound does. Your axle weights for an older bus will be likely be far different than a 45 footer. Greyhound buys the same bus equipped the same way by the dozens or hundreds so they know what the PSIs should be for that model of bus.
Tire inflation numbers are specific to each model of bus. Every bus conversion will need different PSIs due to each bus conversion weighing a different amount and distributing the weight differently.
Jack is right that each wheel should be weighed individually with the bus loaded for travel. I had each wheel on my bus weighed last fall and found I was overinflating my tires by up to 30 PSI. Overinflation won't hurt if you don't exceed the maximum pressure, but the bus won't ride as well.
Jack has a very good point I would imagine every tire would have there own PSI. Good call!
Steve 5B.....
As Jack says, load up your bus with you and whomever normally rides with you, fill the tanks and go to the truck scales to have the bus weighed by individual axles. Then look at your tire manufacturers inflation guide and run the tires about 5-10psi higher then the actual suggested pressure. As example, my 11R24.5 16 ply tires can take 7200lb each in the front at 120psi, and 6600lb each at 120psi in the rear. But since I only weigh 10,500lb in front and 20,500lb in the rear, it works out to be a comfortable 90psi all around. DO NOT run what the max tire pressure says on the side of the tire-you'll get less than optimum tire wear and the bus will ride like a fork lift. With proper tire pressures, you'll be surprised at the excellent ride quality. Good Luck, TomC
IIRC, the MC7-8-9 in commercial service would run 100 front, 85 drives and 75 in the tags.
get your coach weighed and follow the charts for your particular tires for inflation recommendations.
Running the steer tires too high can also contribute to wandering steering.
Running the tires higher than the chart will yield no measurable improvement in fuel economy, running them softer than that point can harm it.
The 45 foot coaches are quite heavy on their own, before loading up with passengers and stuff. The tag axles in particular are carrying close to or equal ratings to the steer axle, depending on the model.
happy coaching!
buswarrior
Do the truck stops have capabilities to weigh each axle independently?
100 front 85 drive and 75 tag now I am a believer, I never would have guessed the tyres pressures would be so diffrent.
John
John, I run 100 psi on all tires and the ride is great, but I have an Eagle and it all depends on the load you carry. Play around with different pressures to see what works best for you. Too high and the ride will be harsh, too low and you might create heat.
~Paul~
I know the average truck scale can't do per tire weights, or if they do it isn't on the standard printout.
Per axle weights are generally good enough unless you are really anal. To get per tire weights the shop I was at had to use a portable scale that went under each tire. I was charged 6/10ths of an hour for this or about $50. I had each tire weighed to be sure I didn't need to have my torsilastics adjusted to even out the weight.
Without water I was within 200 to 300 lbs side to side on each axle.
Fwiw the only wheels you weigh on a Eagle are the boogies the drive are a combined weight, so are the steers. Belfert I am still trying to figure out how you could change side weight on a bus equipped with torsilastics good luck
I might not be remembering the stuff about the Torsilastics correctly. Maybe MCI told me I could change the weight distribution between front and back by adjusting the torsilastics.
I didn't worry about it too much after I had the bus weighed by tire and the steering axle is well below the axle rating. I had the bus weighed at a Cat scale when I drove it home and the Cat scale said I was at 12,000 lbs on the front axle. I called MCI to ask about steering issues on the Dina and the technician was very concerned if I really had 12k on the front axle as that is the rating of the axle.
After a lot of experimenting I finally settled on 90psi all around on my 4104 with 22.5R 1100s. It steers well and rides well.
It is a lightweight though, I figure it only weighs around 2400 when filled to normal running load. This is a very simple conversion which is what I wanted.
I'm sure I could calculate each axle and adjust the tire pressures accordingly, but the Alcoa rims are rated at 105PSI and 100PSI in each tire is a lot easier to remember. So far no problems, handling, steering, or hot tires ;D
FWIW Will
RV Load Inflation (http://www.rvtirepressure.com/assets/images/extrapages/Michelin_Rv_Load_Inflation.pdf) chart.
As always the higher the tire psi the better mpg but harsher ride.
Sojourn for Christ, Gerald
Each tire manufacturer will have a slightly different PSI table. My 11R24.5 Firestones can handle about 300 lbs more than the Michelins at 105 PSI.
I have Kumho 12R22.5 tires on our MC7. I have only been able to find a chart that shows max load at 120PSI. The max load on my Kumho tires is the same as on the Michelin chart (that Sojourner posted) for both single and the duals at 120 psi, so would it be fairly safe to assume the max load at 90 PSI would be the same as on the Michelin chart. I would prefer to run with 90 or 100 PSI and according to the Michelin chart I would still be about 500 lbs under max load at those pressures with their tire.