WANTED: 24.5 wheels

[Elliot Naess]

Sure, it's a long shot, but I'm interested in two wheels in the 24.5 diameter (and tubeless). These will generally be found only on some 18-wheelers. I need "west coast" wheels with ten lug nut holes like a car, and lug-centered. With or without steering tires.

The idea is to increase ground clearance under the front of Millicent. She has 22.5 with "low profile" tires now. Ideally, I'd get the old school 11- or even 12- tire size, rather than the now common metric "low profile" tires. (But new 11x24.5 tires are still available.)

Would need to be on the west coast so I could pick them up on my travels.

[Elliot Naess]

Hi Timmy! Yes, this might be of interest to many of us.

Millicent is a couple inches lower in front than in back, measured along the straight main section of the bottom of the body. This was an advantage when a heater hose came loose from an under-seat heater last year -- all the coolant flowed forward and out the door. But otherwise it is a disadvantage.

Most commonly, I scrape the front bumper in rough terrain -- such as the rural goat-trail I live on. And last weekend I "relocated" a small mountain of sand with the corner of the front bumper while backing into a tight camping spot on a beach. (Quite a bit of sand wound up inside the bus, in the stairwell!) If I had gotten stuck in that spot... we'd have been carrying Millicent out of there is little pieces in our back-packs.

I could raise the bumper and give up a little of the "Peterbilt look", but what I'm really worried about is the mechanical Stuff underneath, like the engine oil pan.

And Millicent is a front-engine bus, so there is a quite long rear overhang. And she has a toy-hauler type tailgate. That "draw bridge" is very steep. Tilting the rear of the bus down, by raising the front, would flatten the ramp a little bit.

I could buy new front springs, or maybe even have the old ones re-arched. Lift blocks are also a possibility. But it seems easier to just swap wheels. And easier to undo if some unexpected problem crops up. Of course, I may wind up doing both wheels and springs. For right now, I'm exploring inexpensive ways to get started on this issue.

[crazycal]

Lift blocks are also a possibility.

That 's what I was thinking about doing to the BB. Some of the truck parts places can custom make U-bolts for you. If you put the larger wheels and tires, will there be any clearance issues.

[Elliot Naess]

Yes, we have Betts Spring across the street from my old trucking yard. I've had them bend up U-bolts for me to use for water tank mounting under Millicent.

I seem to have lots of clearance, but that is one of the concerns, yes. But only the frame rail is "immovable". I can always fix clearance elsewhere. Two words: Power tools.

[busdriver_phil]

I forget, are 11R and 12R the same outside diameter for 22.5" and 24.5" wheels? 12R22.5s are common on city transit buses. There's a big dealer in CA called Transit Sales International, you might have some luck there if 22.5s will do.

I hate low profile tires. Aside from looking puny, they cause lots of ground clearance issues. I drive for First Student, the company that puts them on every school bus. We have one conventional, 77 passenger (longest conventional-nose bus built) with 265/75R22.5s that always bottoms out the rear end. They just had to replace the rear section of the exhaust because of rust, and the pipe stayed round for less than 2 days before someone hit it again pulling into a school driveway (that was designed for buses).

But hey, it could be worse. You could have an AmTran RE like me. Even with its 11R22.5s, the front end sits very low. Just getting over the little dip at the edge of my driveway, the step's about an inch above the ground. The stepwell is bent from when it obviously bottomed out before, and I'm considering not fixing it to keep the extra half inch or so. Unless I do something major with the suspension, I'll just have to live with the fact that I can't take my skoolie to some of the more remote camping areas. But I drive coach buses on the weekend, so I'm used to being somewhat limited in off-road capabilities.

[frank-id]

About 5 years ago, my Crown got 24.5 wheels. My decision was based on, the steering wheel is 15 inches, large wheels work good off roadway, and the tires seem to last longer, because of less RPM per mile. The wheels were purchased at a dealer for Freightliner for $80 each. The wheels are used reconditioned. The wheels were straight and painted. Frank in Idaho

[Elliot Naess]

I am not up on the height of the various tire sizes -- only the general concepts. The "old school" tires, with width-designations like 9, 10, 11 and 12, are taller than the corresponding metric low-profile tires with width-designations like 295/75.

In the 295/75, the 75 means that the tire is only 75 % as tall (bead to tread) as it is wide. The old school tires are closer to as tall as they are wide.

So a 12R22.5 would be taller than the metric tire OF THE SAME WEIGHT RATING. So yes, 12R22.5 would give me more clearance by changing only the tires. But I don't know how much. If I go to 24.5 wheels, I gain one inch ground clearance immediately. The tallest tires possible would probably be 12R24.5. I seem to remember measuring one at work a long time ago, and it was something like maybe 44" tall. Millicent's 295/75R22.5 is around 40". That would be a very worthwhile increase of 2" ground clearance.

Sure wish I had a chart that showed height or circumference of all tire sizes.

(But I can mention this: 295/75R22.5 and 275/80R22.5 are the same height and are used interchangably in the 18-wheeler industry. )

Frank, reconditioned 24.5 wheels for $80 sounds fair enough. I paid only $100 for my new 22.5 wheels four years ago, but I got my employer's "big customer" price -- a walk-in customer would pay more.

[busdriver_phil]

I just answered my own question, I was at a truck show for kids today with a school bus with 11R22.5s parked next to an 18-wheeler with 11R24.5s. There was a clear difference in the diameter of the tires.

Sure wish I had a chart that showed height or circumference of all tire sizes.

http://www.goodyear.com/truck/pdf/edb_dimensions.pdf

[Elliot Naess]

Fabulous chart! I printed it out.

And I see I can get a 12R24.5 tire with diameter around 45". That would be a gain of 2.5 inches ground clearance!

Or keep my wheels and use 12R22.5 as mentioned above - those are 43" -- 1.5 gain.

By the time I get done, Millicent wil look like I'm always driving uphill!

If I can afford it.

[elkoskoolie]

Elliot, I'm pretty sure 12 R22.5 and 11 R22.5 tires require wheels of a different width. This may also effect the rear duallies. Something to look into before making a purchase/decision!!

[Elliot Naess]

Excellent point, Elkoskoolie! And the answers are all right there in the chart that Phil posted the link to. In the league where I'm trying to play -- 11R and 12R, some tires call for 8.25 inch wide rims, and some call for 9 inch.

But I have a hunch I might get away with a bit of mix-n-mis-match. Here is a tire -- G287 MSA (whatever that it) -- where 12R22.5 calls for 9, while 12R24.5 calls for only 8.25.


Edit: The G287 is an All Position tire -- OK for steering, just a bit bit coarser than a pure steering tire. 44.9 " tall in 12R24.5!
Equally tall money, though, I bet.