Correct Tire Pressure

[EastCoastCB]

Originally Posted by Michael_Grumbach

Hi Folks,
We have a 2000 International, 35feet.
Where can I look up the correct tire pressure.
I know what it says on the tire, but I know that's not the best pressure for it.

Also, do I need a special pump or will the generic gas station air pump do?

Thanks,
Mike

Your bus should have the tire PSI specified on a sticker or plate on the front cap inside.
You'll need to go to a truck stop type station for a compressor capable of going 80-120 psi.
Call Navistar with your vin and they can tell you what the factory PSI would be if your data plate is missing. Hopefully you still have it.

[EastCoastCB]

Originally Posted by Michael_Grumbach

this is Deb. the tire pressure on the tire is a MAX pressure. RECOMMENDED pressure is vehicle dependent. the same tires used on a shorty are used on a 40' bus and these vehicles weigh different. therefore there is a RECOMMENDED pressure for the vehicle based on THAT vehicle.

much like on a car where the max pressure is probably around 44psi depending on the tire but a car or minivan would have a max psi on the door tag of around 35. you want to inflate the tire as appropriate for the vehicle without exceeding the max pressure for the tire.

thus we are trying to find the proper pressure for our bus.

You're quite correct. Different buses call for different tire sizes, plys, psi, etc.
You'll get best tire life and ride if you follow the bus manufacturer's #'s.

[mmoore6856]

Originally Posted by magnakansas

There are charts published by tire builders, they will show minimum pressures recommended for the amount of weight the tire carries.

You have to know, not guess, KNOW what the load is, Then look up pressure chart.

I run below max pressure only because I am seeking a less thumpy ride. I will air down in loose sand, high risk move because of taking the tire off the rim.

Spend the time looking and or go to the truck tire store and get the charts.

Also recommend air pressure monitors. Good ones mount inside the tire and watch heat also. Not cheap.

William

finally somebody that knows something. the listed pressure on the tire is for the maximum weight. weigh your bus and see what it weighs as if your on the light side you can run less. never exceed the max listed on the tire.

[Rock-N-Ruth]

Originally Posted by Oscar1

Hello Deb
RECOMMENDED pressure is not vehicle dependent, it's load dependent. Pressure less then what is on the tire is considered for comfort. Putting that tire on a five window shorty that weighs 50% less than a 40' bus doesn't mean you can reduce the tire pressure, if it rides rough you change the suspension not the tire pressure. Less than 90psi is considered under inflated.

Just an additional warning to this excellent answer, running under inflated tires on your bus can lead to disastrous consequences.

[HamSkoolie]

Originally Posted by Rock-N-Ruth

Just an additional warning to this excellent answer, running under inflated tires on your bus can lead to disastrous consequences.

Yeppers. Let's not forget the massive Ford/Firestone fiasco that was partially caused by underinflated tires on the Ford Explorer which contributed to heat build up, premature aging, and tire FAILURE resulting in deaths and injuries.
The tires involved in that controversy were designed for 35psi but Ford published inflation on the Explorer at 26psi (and Firestone warranted them at that pressure but they weren't designed for it)....and hundreds died.

But hey, that was 20 years ago. Ancient history doesn't count....does it?

[sportyrick]

I had my tires over inflated because my service truck is very top heavy and 33,000# heavy. I eventually blew all 4 rear tires on the same day, first one then another then two together, it was a $2500 day and hours sitting in the heat waiting for a tire truck. Yes the truck had sit a few years probably underinflated then I bought it and I started driving it but it was scary with just the normal pressure so I bumped it up 10 pounds to 120. Of course it was the hottest day of 2019 at 103, running on I-70 over to St. Louis for 2 hours didn't help by making the tire temp so high which runs the tire pressure through the roof and boom!. Also they were 11 years old and cheap to begin with. Tire pressures are designed to compensate for temp extremes but they will only take so much. I would say never over-inflate.

[shorthair]

You can use the numbers on the tire and an accurate axle weight to get the air pressure for your load, or just do it the easy way with a chalk line and drive in a straight line to see if the line wears evenly.

[BFlinn181]

Originally Posted by Iceni John

Weigh each corner, then look up the recommended pressures in your tire manufacturer's chart of pressures. There really isn't any other way to do this.

John

I agree with John's suggestion above. A school bus goes from empty to full of kids each trip. The tire pressures listed on the sticker is for the maximum load, not empty. In a rebuilt schoolie, your weight doesn't vary as much as a school bus. After you built it and load it for your first adventure, stop at a truck stop and weigh it on the CAT scale. You could also perhaps use a scale at a grain store or the like. Once you know your axle weights, go online at the tire manufacturer and use their charts. You'll have a better ride and still be safe.

[BigPaul367]

Originally Posted by Michael_Grumbach

Hi Folks,
We have a 2000 International, 35feet.
Where can I look up the correct tire pressure.
I know what it says on the tire, but I know that's not the best pressure for it.

Also, do I need a special pump or will the generic gas station air pump do?

Thanks,
Mike

Okay, here we go!

Tire Pressure? Do you want best fuel economy or best tire life?

Best fuel economy? Fill the tires to the maximum it says on the tire and keep it there.

Best tire life? Get a thin note book, draw a schematic of your tires locations. Get a tread depth gauge, measure across the tread depth in the same place every time, twelve o'clock (,the valve stem is a good place for twelve three o'clock, six o'clock, nine o'clock. Write the measurements down and check those measurements every 3,000 miles. Adjust the pressures until your record equal wear across the tire tread. This will provide a snapshot into the tire life of your Skoolie.

This will be required for the life of tires and will constantly need to be monitored.

Different brands of tires will wear differently.

Never put retread tires on the front of anything that travels long distance and high speed. New tires on the front is always best.

I like to put each axle on jack stands, off the ground, and spin them while I watch for tires that are out of round, improperly mounted or treads that are not aligned with the carcass correctly when they were retreaded.

[Sehnsucht]

Without rehashing too much of the good feedback already proffered...

The tire pressure RECOMMENDATIONS on the vehicle's data plate are based upon the manufacturer's specs when the vehicle was built for it's intended purpose, in most of our cases, as a school bus. The math involved in calculating the anticipated weight of a full bus of passengers was what determined the tire the manufacturer installed when they shipped it out.

Fast forward 15-20 years and we're not using the bus for it's intended purpose anyways so the vehicle data plate isn't all that relevant. Also the used bus has possibly been through multiple sets of tires so what's installed when you get it used isn't necessarily the manufacturer recommended tire, in fact it's possibly less than minimum standard because they swapped off that current good set for the oldest cheapest set of spares they had lying around. So don't believe the sidewall as gospel for what your rig requires.

It's already been said here repeatedly, find a CAT scale and weight your rig. If it's unfinished, add a margin for what remains to be installed. If it's finished, fueled, and full tanks then add as much as your passenger weight (no need to lie, we're not Weight watchers here!). Then shop for a tire that has a comfortable margin weight capacity above this presumed maximum weight. Remember you can split the weight across duals but steer tires work alone and MUST be able to carry the weight. A steer tire blowout is much more chaotic than a drive tire blowout. Then run that tire at the tire manufacturer recommended pressure for best performance and longevity.

[Mekanic]

Originally Posted by o1marc

On the side of the tire.

Yes Its (Cold pressure) ON The side of the TIRE!!