Tire size

[Ed Hackenbruch]

I had 11 r 22.5s on my bus and could roll down the hiway at 70-75 easily.

[6805eagleguy]

I would go for a little more aggressive tread on the back. Not fun to get 'stuck' on wet grass.

Right now I'm running Goodyear endurance wha steer tires... just what the local tire man recommended
Right now I have 30 miles on them, we'll see how they work in there long run

[richard5933]

It's almost impossible to compare top speed in one bus to another based on tire size alone. There are so many variable in the equation and it's difficult to get an apples to apples situation. The better question is how you thought your bus did with the 12R tires? I know that you only had a short ride with it, but you hopefully got some idea.

My GM 4106 had an 8V71 coupled to a V730 and had 11R tires. My current bus (GM 4108) has an 8V71 coupled to a Spicer 4-speed and rides on 12R tires. I don't notice any difference on the lower end at all between the two, but the 4108 can hit 80mph easily if I want it to. But, there are so many other variable (rear axle ratio, trans gear ratios, engine strength, etc.) that there is really no way to know specifically how much difference the tires make without doing lots of math. I hate math.

[luvrbus]

From what I've seen the 295/80R22.5 is no easier to find than the 12R22.5. Not any cheaper either last year when I went shopping. Might be different now.

Here's a chart I did when I was tire shopping to compare the options. I ended up going with the 12R22.5 as they were the closest to the OEM tires.

I bought 6- 295/80/22.5 from Les Schwab in the small town of Ontario Or so they must be to hard to find ,I had my choice of the 12Rx22.5 or the 295/80/22.55 fwiw the 12Rx22.5 is a bus tire and they can be tricky to find without ordering

[RJ]

I think stock was 12R-22.5.

There should be a builder's plaque somewhere on your coach, the stock location was above the driver's left shoulder riveted to the roof.  If your bus was professionally converted, the converter may have moved it elsewhere (on my '78 5C, Angola riveted it to the inner door of the electrical compartment under the driver's window.)  Not only will it have the month/year of the build, but also the Serial Number and the Unit Number. In between the date and the VIN, it will indicate the GVWR as well as the GAWR for the front and back axle when using the tire sizes recommended on the plaque.  99.99% chance it's going to say 12R22.5s.  But look anyway.

Also, look at your outside dual. Chances are you'll find the wheel size (diameter & width) stamped into the wheel rim somewhere, often opposite the valve stem hole. If you've got stock steel wheels, again, chances are they're 22.5 x 8.25.  (Side note: if a PO changed the wheels, and you've got 22.5 x 9 or 22.5 x 9.5, you're in luck, because you can now run 315/80R22.5s if you want.  Just can't put those on the narrower 8.25" rims any longer.)

Finally, the fellow who now owns the MC-5C I used to have, changed all the wheels over to 24.5s and is running 11R24.5s. He's gone for the taller tires to reduce the rpm while running down the highway and hopefully increase the fuel mileage a little. He's been in the trucking industry for years, and I understand he's running Coopers on it now.

FWIW & HTH. . .

[richard5933]

...Side note: if a PO changed the wheels, and you've got 22.5 x 9 or 22.5 x 9.5, you're in luck, because you can now run 315/80R22.5s if you want.  Just can't put those on the narrower 8.25" rims any longer...

I've seen notes in at least two manufacturer's tire spec books (Firestone & Michelin) listing 315s tires on 8.25" rims, but at lower max. air pressure and a slightly de-rated max capacity. I wouldn't recommend going this route, but it does provide options if there is ample clearance and you should run across a great deal on some good used tires.

[sledhead]

on my coach I put the tire size and vin.# to the left of the driver seat so it was easier to see and all tires are the 295/80 r22.5 and if you look in the pic. you can see it to the left of the thermo .

never had a problem getting this size of tire and my tire guy did say there are still used on a lot of trucks , rv's  and bus

https://lh3.googleusercontent.com/pw/ACtC-3fRzB9TFTrMZDgf3aLXwTPNDkYVfwVuC73cFnms1RZLohddnH7-3ss28mumhny2laSC8sduDDGKL698ZqE8AyGWU8SPcRjYZKe7xvKnvdPUJ3j0tIc7XzKN-tqUOcdOXQb1fXuuwV0VQNb_35DS75Tw=w1157-h867-no?authuser=0

dave

[Jsrcaptain]

I looked at my placards, all six, lots of information, weights etc., but no tire size. I'm sure everything is still stock.

The PO was the second owner. The first was the US Air Force. It spent it's early days in Colorado Springs, running back and forth from the airport to the Air Force Academy, so, not many miles and not much rust. Probably driven by inexperienced airmen as the sides are creased badly from tight turns. They took out a lot of stop signs I'm guessing.

[luvrbus]

I looked at my placards, all six, lots of information, weights etc., but no tire size. I'm sure everything is still stock.

The PO was the second owner. The first was the US Air Force. It spent it's early days in Colorado Springs, running back and forth from the airport to the Air Force Academy, so, not many miles and not much rust. Probably driven by inexperienced airmen as the sides are creased badly from tight turns. They took out a lot of stop signs I'm guessing.

The  12R x22.5 was standard issue for the MCI even up to the D models,bus people and tires lol you see up to 3 different size tires on the newer buses OEM my rv has 295/80/22.5 on the drive axle and tag axle and 315's on the front axle came from the factory set up like that according to the chart 

[chessie4905]

The GMC  4905 service manual lists 12r, 12.5r and 13r x 22.5 tires. My spare coach has 12.75's on the front. Firestone lease tires, and didn't show any cracks in the sidewalls till about last or year before. They apparently use better rubber in their tires that they lease.

[chessie4905]

Price will help you decide. Generally 12r are noticeably more expensive compared to 11r, due to less demand. Also, consider Bandag or Michelin retreads for the rear. Remember that you'll never wear a set out unless someone else is footing the fuel bill. My dad wore out a set on the 4104 but fuel was less than $1.00 a gallon for a lot of those years. And he got 8 to 10 with the generator using from same tanks. 

[Jsrcaptain]

That's kinda what I was thinking. Not enough years left to wear out a set of tires. I won't be circling the globe, mileage-wise that is. Gotta have some money left at the other end to eat.