Tire Suggestions for 4x4 School Bus

[baipin]

22.5" tires range from about 36" - 41" diameter

avoid 2-piece and split ring rims like the plague because getting a tire shop to change them is becoming quite hard due to safety issues

if you are bound to do your own centers Dayton makes 22.5" centerless rims that replace the older 20" Daytons that came on school busses and dump trucks etc and fit directly onto the original Dayton 5 spoke hubs

good luck with your project

"T"

I'm partial to the 1100x20 Michelin XLs but that's because I used to drive 5 tons that had those. The 11R22.5 tires are found everywhere and relatively cheap.

Thanks for the replies!

Oh yeah, not going with split ring rims - I had to remove the worst offenders off this bus; Firestone RH5 "widowmakers". That was a thrill I don't want again! I'm assuming in spite of being 2 part, the Humvee rims (or military 20's) are safe as they're bolt together and have multiple points of failure rather than one point of failure with the split ring.

This bus never had Dayton spokes, only the heavier 35+ ft., class 6 and up, GMC buses of the era did as an option. Daytons are cool though, very rugged.

I'm thinking I may go with 22.5's. about 200lbs per wheel + adapter + tire for military 20's seems a bit much. I've found 10x285 to 8x6.5 adapters for a great price. My main worries...
- The sheer mass of 22.5's on a Dana 60. Is it too much for something that isn't a mall crawler on alcoas? I keep receiving conflicting answers on this. I currently have the later OEM shafts which do NOT neck down at the splines (no relatively weak area). Are chromoly shafts or 35 spline a nice upgrade or absolutely necessary? Granted I'm not wheeling this thing hard; some occasional mud and bumpy, rocky trails, but mostly fire service roads and logging roads, no rock crawling in something this size.
- Suppose they'd also ride rougher than the humvees.
- Rear driveshaft is 1410, that's also the largest I can go up front. I have 4.56 gears and intend to keep it that way. Would 22.5's necessitate a regear and/or larger driveshafts? I spoke with some guys at Tom Wood's who said 37" would be absolutely fine with the current setup, but couldn't say much about 41" tall tires on 22.5's.
- Is losing beads/inability to air down a hindrance even with mild off-roading for 22.5's? I will also likely be running a DRW rear with the 22.5's as I cannot find any 22.5" rims suitable for SRW use that isn't for some massively wide on-highway single.

Some advice, especially with the first question, would be much appreciated. Thank you.

 

[shortbus4x4]

Ahh the old Firestone RH5 rims, those were the widow makers that gave all rims that have a lock ring a bad name. I have no problems with rims that have lock rings, as long as you take proper precautions airing them up. I currently live in farm and logging country so tire shops around me have no issues with "split" rims.

How much weight is the front Dana 60 going to support? I think that is going to be the question you need to answer. What was the front GAWR for a 80s Chevy K30? I think your Dana 60 will be ok with 11R22.5 tires as long as all the kingpin/steer components are in good shape and you aren't maxed out on front end weight. You'll also want to have your steer tires balanced. Even on Forest Service roads you will be in 2 wheel drive 99.9% of the time, if you rock crawl the bus then all bets are off.

 

[baipin]

Welp, for a number of reasons the BFG Baja Humvee tires seem to be the way to go. Cheap enough that if I hated them it wouldn't be a major loss, but new enough that if I like 'em, they'll last a while. I think they look great:



I mean hey... it's not like I could go much bigger anyways lol - 1/2" to spare (it'll have considerably more room with the lift, so just imagine this as the tire at full spring compression):



Moved the tires down 6" in Photoshop, where they'll be when the bus is lifted:



Thank you everyone for the variety of advice on this! Much appreciated.

 

[BBD]

looking good - do you have a build thread for the whole project?

 

[baipin]

looking good - do you have a build thread for the whole project?

Thank you! Sort of have one on Irate: https://irate4x4.com/threads/1959-gmc-2-ton-bus-4x4-swap.387134/page-1
Also have the bus on IG: https://www.instagram.com/thatbuschoseme/

I'll make a thread here on Expo this afternoon. Plenty of stuff I'd like to share that isn't really geared towards Irate, like batteries, solar, etc.

 

[BBD]

That thing is going to be awesome! Thanks for the links.
My build will be a similar gvwr ~14,000lbs. (mt45 4x4 conversion) so, I'll have to look into those hmmwv tires.

For anyone else looking at tires / wheels for something of similar size - I've been posting at diesel place on wheel / tire options. There's an interesting 20" option from Hutchinson.

Info: - 20" single wheel options, Kodiak/Topkick...

www.dieselplace.com

 

[baipin]

That thing is going to be awesome! Thanks for the links.
My build will be a similar gvwr ~14,000lbs. (mt45 4x4 conversion) so, I'll have to look into those hmmwv tires.

For anyone else looking at tires / wheels for something of similar size - I've been posting at diesel place on wheel / tire options. There's an interesting 20" option from Hutchinson.

Info: - 20" single wheel options, Kodiak/Topkick...

www.dieselplace.com

Thanks dude! Yeah, 14,000lbs seems a good target to aim for. Curb weight of my bus is about 9,500lbs. Most long wheelbase sprinter conversions and shorty buses r are around 2,000-3,000lbs for the interior conversion. My bus, and I'd assume a MT45, are not that much longer than the longest wheelbase sprinters or shorty buses.

The Humvee tires when used with 24-bolt asymmetrically-spaced wheels (the latest version) are rated for 4,540lbs. That's great as you could theoretically have an 18,000lb GVWR. However, I've found front axle weights to be the limiting factor.

Any idea what axles you're using? A Dana 70 or 80 will let you maximize your GVWR for the rear. However, a Dana 60 is only rated for 4500 to to 6500lbs for those that can fit Humvee tires. With 9,000 on the rear and 5,000 on the front you've got 14,000 total, but you're pushing the tire rating on the rear and pushing the axle rating on the front. I'm sure it's safe, but there isn't much wiggle room. I made some drastic upgrades to my kingpin 60 front (Jantz loadbolt, 35 inner/outer, Warn hubs, gusseted and trussed all over the place). It'll hold plenty, but I'm not certain how much...

 

[BBD]

Thanks dude! Yeah, 14,000lbs seems a good target to aim for. Curb weight of my bus is about 9,500lbs. Most long wheelbase sprinter conversions and shorty buses r are around 2,000-3,000lbs for the interior conversion. My bus, and I'd assume a MT45, are not that much longer than the longest wheelbase sprinters or shorty buses.

The Humvee tires when used with 24-bolt asymmetrically-spaced wheels (the latest version) are rated for 4,540lbs. That's great as you could theoretically have an 18,000lb GVWR. However, I've found front axle weights to be the limiting factor.

Any idea what axles you're using? A Dana 70 or 80 will let you maximize your GVWR for the rear. However, a Dana 60 is only rated for 4500 to to 6500lbs for those that can fit Humvee tires. With 9,000 on the rear and 5,000 on the front you've got 14,000 total, but you're pushing the tire rating on the rear and pushing the axle rating on the front. I'm sure it's safe, but there isn't much wiggle room. I made some drastic upgrades to my kingpin 60 front (Jantz loadbolt, 35 inner/outer, Warn hubs, gusseted and trussed all over the place). It'll hold plenty, but I'm not certain how much...

View attachment 752616

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Looks like you turned your Dana60 into a Super 60! I think that I-beam style beef is a good idea for snow / rust maintenance compared to other configurations I've seen.

Re: Axle / Weight Ratings - I think I found a 'unicorn' - supposedly surplus Dana 70 front drive axle from a 2019 International CV with manual locking hubs from Warn. It happens to have the same bolt pattern as the MT45 and same axle width as my rear axle, of which, mine is the smallest ever made at 138" WB, and 20' long bumper to bumper. My 14K GVW seems mostly limited by the rear Dana80 Axle with single rear wheels, compared to the longer bodies with (dual rear wheels) & higher ratings since that seems to be the only different components. So, for axle strength, I should be good to go for a little over 18K lbs. The longer MT45's are rated around 19,000lbs I think.

Re: Buildout - Your estimates sound right to me as a comparison to the sprinters. I found those to be too narrow, and wanted plenty of extra payload for heavy (and important) things like fuel, water, batteries which can quickly overload smaller vehicles.

Re: Wheels / Tires - I had a crazy idea after thinking about those humvee tires. The weight ratings seem just right for my build as well compared to going with tires/wheels that are rated more than 2x my gvwr. I found a backhoe (front) wheel that matches the specs of those tires, and the bolt pattern on my axle... Who knows how it would do at highway speeds. Anyone heard of someone using an agricultural / construction wheel for on-road application? https://www.gallaghertire.com/16-5-9-75-8-275mm-case-cb-8-70-a16597570.html

 

[baipin]

Looks like you turned your Dana60 into a Super 60! I think that I-beam style beef is a good idea for snow / rust maintenance compared to other configurations I've seen.

Re: Axle / Weight Ratings - I think I found a 'unicorn' - supposedly surplus Dana 70 front drive axle from a 2019 International CV with manual locking hubs from Warn. It happens to have the same bolt pattern as the MT45 and same axle width as my rear axle, of which, mine is the smallest ever made at 138" WB, and 20' long bumper to bumper. My 14K GVW seems mostly limited by the rear Dana80 Axle with single rear wheels, compared to the longer bodies with (dual rear wheels) & higher ratings since that seems to be the only different components. So, for axle strength, I should be good to go for a little over 18K lbs. The longer MT45's are rated around 19,000lbs I think.

Re: Buildout - Your estimates sound right to me as a comparison to the sprinters. I found those to be too narrow, and wanted plenty of extra payload for heavy (and important) things like fuel, water, batteries which can quickly overload smaller vehicles.

Re: Wheels / Tires - I had a crazy idea after thinking about those humvee tires. The weight ratings seem just right for my build as well compared to going with tires/wheels that are rated more than 2x my gvwr. I found a backhoe (front) wheel that matches the specs of those tires, and the bolt pattern on my axle... Who knows how it would do at highway speeds. Anyone heard of someone using an agricultural / construction wheel for on-road application? https://www.gallaghertire.com/16-5-9-75-8-275mm-case-cb-8-70-a16597570.html

It essentially is a Super 60 now, I'd say... Smaller, low pinion ring gear, yes... but a load bolt to prevent deflection. I could upgrade to 70 ring and pinion, but I need to put funds elsewhere in the build and it's more than strong enough for my needs, anyways. The inner C's have been gusseted such that they have at least the same amount of metal as 70 front C's. Good catch on the I-beam design. That is exactly why I went with such a design over a box girder. We get so much snow and roadsalt here that being able to clean it after driving is important. This design also let me put a "bumper" on the I-beam flange; a 3/8x3/8 strip of stainless steel. It'll take the brunt of an impact and not need to be painted over and over again.

Can you share pics of the International 70 front? That's a great fine - congrats! Is it the same as the Topkick 70 front? I've always wondered what axles those new International trucks had...

Far as wheels go; I've wondered about heavy equipment 16.5's as well. Could be an interesting option, and they're often three piece locking ring rims as well. Would really need to see how they handle at speed though, but potentially promising!

You can find my build thread here by the way: https://expeditionportal.com/forum/threads/1959-gmc-adventure-bus-build.236147/#post-3065613

 

[BBD]

It essentially is a Super 60 now, I'd say... Smaller, low pinion ring gear, yes... but a load bolt to prevent deflection. I could upgrade to 70 ring and pinion, but I need to put funds elsewhere in the build and it's more than strong enough for my needs, anyways. The inner C's have been gusseted such that they have at least the same amount of metal as 70 front C's. Good catch on the I-beam design. That is exactly why I went with such a design over a box girder. We get so much snow and roadsalt here that being able to clean it after driving is important. This design also let me put a "bumper" on the I-beam flange; a 3/8x3/8 strip of stainless steel. It'll take the brunt of an impact and not need to be painted over and over again.

Can you share pics of the International 70 front? That's a great fine - congrats! Is it the same as the Topkick 70 front? I've always wondered what axles those new International trucks had...

Far as wheels go; I've wondered about heavy equipment 16.5's as well. Could be an interesting option, and they're often three piece locking ring rims as well. Would really need to see how they handle at speed though, but potentially promising!

You can find my build thread here by the way: https://expeditionportal.com/forum/threads/1959-gmc-adventure-bus-build.236147/#post-3065613

Sure, I'll see what I can do to get a photo of the Dana70. I believe the Topkick / Kodiak use a Dana70 up front, but not sure how it would differ from this. I've been watching the various Kodiak builds as it's a very similar size/weight/gvwr to the mt45.

RE:16.5" wheels - I didn't even think about it when posting, but there's no way those would fit over the hubs / rotors on my build, so 20" wheels it is!

Thanks for the build link - will check it out.

 

[baipin]

This would be interesting. I wont be surprised an 'agri wheel needed balancing weight added. Especially if it has stem guards..
And for the paranoids, its possible it wont bear DOT markings either.

Those stem guards look tacked on. Wonder if you could just grind 'em off? Could be an interesting option...