22 or 24 tires?

[daddysgirl]

Happy Sunday all.

Clifford reminded me about a question I wanted to ask in a comment on a different thread.
I currently have 12R 22.5 tires on the bus. I have been thinking of changing them to 24's, but I wanted to get input from you all.

I know the effect of different tires on cars and Jeeps, but rather than assume, I thought I'd ask.

Thoughts?

[Lin]

Which one is most easily available on the road?

[HB of CJ]

My old long gone Crown Supercoach had 12R 22.5 tires.  Some help here please ... does the 12R 22.5 require a slightly wider wheel?  Or can you use a standard 22.5 wheel in an emergency?

I almost bought a complete set of Michelin 11R 24.5 tires and Alcoa wheel take offs from a wrecked highway truck tractor.  Are the 11R 24.5 tires and wheels becoming harder to find nowadays?

Going to the Alcoa wheels would have required longer studs.  Expensive.  I think the revs per mile with both are nearly the same.  Perhaps the 11R 24.5 tire is just slightly taller?  Is this important?

In my case it did not matter.  There was plenty of room in the wheel wells for chains.  The take off tires were just a little bit too old and the price for the swap just a little bit too $high$.  Good luck.

Sorry for choppy post.

[gumpy]

Used to be 24.5 was easier to get. Now, that seems to have changed. I changed to 24.5 years ago because finding 22.5s at that time were sketchy.

I just replaced two steers this summer. Found difficulties finding wheels. Tires were not to bad to find.

Unless you're planning on changing out all your wheels, I would stay with 22.5.  There's really not much benefit to changing to 24.5s.

[ol713]

   HI;
      A year ago I went with 315 80 22.5.  I understand they are way more
      tire than is needed, but I found they are easier to come by. I put used
      on the rear and new on the front.  The used tires were only $150 each
      and less than two years old.
      If you go with 24's you will also need wheels.  Shop carefully.
                                   Good luck,   Merle.

[Scott & Heather]

I put 24.5's all the way around on Alcoas.
I like the slightly lower profile tire/rim ratio.
I looks a little unique. I like it. Your preference though.

[Geoff]

I always wondered if the 24.5's rode harder since there is less tire to ride on than the 22.5's

--Geoff

[kyle4501]

A shorter tire sidewall may make a blowout easier to deal with . . .

However, if I was looking to change - I would look at what the current most popular tires are & choose from that list.

[TomC]

Tire sizes-275/80R-22.5 (Michelin low profile) and 295/75R-22.5 are about the same diameter at 517rpm. Then comes 11R-22.5 at 495rpm. Then the low profile 275/80R-24.5 and 285/75R-22.5-once again about the same diameter at 501rpm. Then next bigger is the 12R-22.5 and 315/80R-22.5 at 485rpm. The biggest diameter tire is the 11R-24.5 at 476rpm. You can see by the rpm differences, you can get a slower running engine at the same speed by going to a bigger diameter tire. I have 11R-24.5 tires that have big sidewalls. I use them mainly because that was what I ran on my trucks. And because my transit bus is lower. On my truck conversion, I also have 11R-24.5 to make the truck higher since I have 28" diameter fuel tanks-of which Kenworth would only put on trucks with 11R-24.5's. 24.5's are mainly used in North America and Canada (popular with the loggers). 22.5 rubber, which can be many sizes-235/80R, 255/70R, 265/75R, 275/65R, 275/80R, 295/75R, 295/80R, 315/80R, 385/65, 425/65, 445/65, 445/50, 455/55, 8R, 9R, 10R, 11R, 12R, etc. So when someone says they have 22.5 rubber-it means nothing without the actual size of the tire. Good Luck, TomC

[Tom Y]

I went with 11R 24.5 to go with a 4 stroke engine and a 740 trans. Now I have a 6 speed trans, using only 5 of them. So wishing I had 22.5 rubber now.

[Dreadnought]

I have been considering changing my wheels/tyres to 24.5 diameter to raise the gearing on my bus. I just changed the steer tyres to 11R x 22.5. I have been pondering all the above considerations to weigh my choice so am interested in understanding too. My rears are currently 12R x 22.5

[eagle19952]

what did the engineers who designed it say ?

[luvrbus]

what did the engineers who designed it say ?

12R x 22.5 but what the hell do they know 

[eagle19952]

12R x 22.5 but what the hell do they know 

hopefully what met the DOT spec for the loads 

[bevans6]

The data tag for my bus -1980 - specifies a bunch of obsolete tires that are no longer available for any price, so that's a tad moot.  12R22.5 is what's on it, and the tire load weights for the rear are off the low end of the scale for those tires on the load-inflation chart.  Even the fronts are barely on the chart.  So I could use 11R-22.5 and save a ton of money and have higher RPM's as a result.  Or I could buy 12R22.5's at a premium, or look for used 315-80 22.5 since they are real common around here on logging and dump trucks.  Any MC-5 is going to be fine from a loading perspective with 11R-22.5, and a MC-7 might be, but I would weigh the front axle first.  I don't think I will go with larger diameter tires with new wheels to save .05 mpg and lose hill climbing ability from the taller gearing.  If someone dropped off a set of good tires on wheels that fit I would probably run them, though...

Brian