Tire Suggestions for 4x4 School Bus

[baipin]

Hello everyone,

Haven't posted much about the project on these forums, but nevertheless, I'm converting a 23 ft., 1959, GMC/Wayne school bus to 4x4. Dana 60 front, probably an 11.5AAM or Dana 80 rear end... This bus is a lot of fun, but one thing I'm struggling with right now, is tire choices.

Ideally, I would like a tire 37" to 43" large. I want a mild offroad tire with good tread life and road manners being most important; I'm expecting the majority of my time to be spent on, let's say; 60% paved; 25% on gravel/dirt logging roads; and 15% on somewhat muddy, unmaintained forest trails. So far, I'm leaning towards either 2016 (85% tread remaining, $375 ea.) or 2019 (new, $550 ea.) BFGoodrich Military Baja T/A 37x12.50R16.5 humvee takeoffs with the 24 bolt wheels included, in a super-single configuration. They are economical, about the size I'm looking for, it's a beadlock and I can service the tire myself, it has an excellent load rating per tire/wheel, and from what I've heard are good for mild offroad, good on road. That said I've heard very little about this tire - the latest generation of Humvee tires - and its tread life.

Other tires I've considered are the 9.00R16 XZL and 325/80/R16 XML. I've heard the latter is bad for tread life, and I can only find the XZL with 2013 date codes. The 11.00R16 XZL would be fantastic but I've never seen them for sale. I've thought about 20" tires, but finding wheels with my bolt pattern, and a 20" rim, in either SRW or DRW configuration, that aren't some garish alloy wheels, has proven difficult. I have considered 22.5 semi wheels, but the adapters are outlandishly expensive; about $1400 for all four corners.

The front Dana 60 axle has an 8x6.5 Chevy/GM bolt pattern and has the spacers necessary to pair it with a dually rear end. I do not have a rear end yet, but anything with a 9k GAWR or greater will suffice.

I've attached pictures of the bus with the Humvee tires, photoshopped to scale, below:




The bus as it sat originally (note, the D60 up front adds 6-7" of lift. Also note, the original tires are 35" in the front and 33" in the rear):



For anyone curious, the mocked-up tires were taken from images here, of an identical Chevy Viking chassis with the 36" Military OZ tires: https://topclassiccarsforsale.com/chevrolet/474571-1958-chevrolet-viking-4x4.html

I'm trying to keep my wheel/tire budget around $2700 or less. Tight, I know. But it's a big project with a lot of other things to tackle. Some advice here would be much appreciated. Thank you!

 

[nitro_rat]

I think that thing needs a 19.5 or 20" wheel to look right. There are lots of Military sizes for 20's...

 

[baipin]

I think that thing needs a 19.5 or 20" wheel to look right. There are lots of Military sizes for 20's...

19.5's would be awesome, but I'm yet to find any AT/MT options in a larger size than the Humvee Baja (37") or 325/85R16 XML's (38.5"). Largest I could find was 305/70R19.5 Michelin XDE2+. If you can think of anything larger, do let me know.

20" would be great, but the MRAP wheels are expensive, I don't know of anyone in Canada who can manufacture custom wheels, and as of yet I haven't come across off-the-shelf aluminum 20" truck wheels with the correct weight capacity (I need at least 4,000lbs per wheel, for the rear). I don't think there are any relatively inexpensive, strong, basic, steel 20" wheels with an 8x6.5 pattern. Hopefully I'm missing something, because if I could find a way to make 20" work within my budget, that would be ideal...

Any idea what on-road wear is like for the XMLs, versus Humvee Bajas? Even if I can't run 20" XML's, I can still find them in a larger 16" size.

 

[nitro_rat]

XML's don't wear in any recreational application that I've ever seen them used in. Maybe a 22.5 super single could be a good choice?

 

[javajoe79]

I went with the hummer wheels for by build at first because I'm not really going anywhere yet but I will be upgrading to 17s at least as tire choice for a 16.5 is very limited and expensive unless you're using surplus.

 

[baipin]

I went with the hummer wheels for by build at first because I'm not really going anywhere yet but I will be upgrading to 17s at least as tire choice for a 16.5 is very limited and expensive unless you're using surplus.

Fortunately, I live close to the militarytires.ca guys, so, getting newer humvee tires (between 1 to 6 years old) is not much of an issue. I do worry about long-term availability though. My understanding is the US nat'l guards will always use humvees, and the humvee will always have an ambulance role as the current JLTV replacement is too heavy or something... But still, I worry about if I need a new one while on the road.

That said, I'm yet to find someone who sells 20" tires newer than 8 years old here in Canada, and all the surplus ones are nearing 10 years old. I assume the same rules still applies; don't run 10+ year old tires regardless of the vehicle they're going on, if it goes highway speeds? As far as military tires go, humvee tires are a lot easier to find.

Using 17's would probably be ideal. But, I don't know of any in the 37"+ range on anything smaller than 20" wheels, that have a load rating of 3900lbs or greater, which is really the bare minimum for my rear axle, unless I go duals. If I could find some, that'd fix my problems. What are you planning on running? I do worry about running LT tires on a rig as big as mine. If I go duals with LT tires 37" or larger, it seems expensive and at that point it'd be cheaper to get 20" rims + military surplus 11R20's (but I haven't seen any commercially available steel ones for 20" - no one seems to make super single wheels in Canada, and shipping + exchange for 1stAttacks is pricey. The 20" tires seem a tad too heavy.

I could buy cheapo surplus 22.5" wheels for $70 ea. and 11R22.5 truck tires, run as duals (new, they're the same price as the used 11R20 military tires I've been able to find). The advantage of 22.5" rims is obviously widespread tire availability and durability. The price of 8 to 10 lug adapters is ridiculous though. I also worry about rocks pinching between both sidewalls of any dual rear setup, and blowing both tires.

I assume you went through similar thoughts with your rig? What's making you pull the trigger on what I'd assume are LT tires in 17"?

 

[nitro_rat]

Medium duty trucks in general just aren't very good off road. I know several guys who have converted medium duty (top kick size) dump trucks to 4x4. All it does is make the stuck worse and the extraction more expensive. Hate to rain on your parade but you'll do better to pick a set of truck tires that are suited to the size and weight of your rig than to try to put a medium duty truck on light duty truck flotation tires.

An 11R22.5 is about 42" tall IIRC. Aggressive tread will be counterproductive. Your truck isn't going to be heavy enough to blow tires from rocks wedged between the duals...

 

[baipin]

Medium duty trucks in general just aren't very good off road. I know several guys who have converted medium duty (top kick size) dump trucks to 4x4. All it does is make the stuck worse and the extraction more expensive. Hate to rain on your parade but you'll do better to pick a set of truck tires that are suited to the size and weight of your rig than to try to put a medium duty truck on light duty truck flotation tires.

An 11R22.5 is about 42" tall IIRC. Aggressive tread will be counterproductive. Your truck isn't going to be heavy enough to blow tires from rocks wedged between the duals...

Well, if you don't think DRW with rocks is an issue with this light of a weight, that's probably alright then as the 22.5 10-lug wheels are the next-best option. Overall diameter, capacity availability, and cost (surprisingly) are strong points here. 20" military wheels and tires are just too heavy and difficult to find with good date codes.

I'm not sure I understand what you mean about aggressive tread being counterproductive? For what it's worth, this bus will mostly be going down abandoned logging roads, FSRs, that sort of thing. Not intending to wheel it hard - a bit of light mud, but nothing crazy.

In any case, a bus about the same size as mine, on Humvees: https://topclassiccarsforsale.com/d...agon-school-bus-4x4-cummins-turbo-diesel.html

 

[nitro_rat]

Once a medium duty truck breaks traction all aggressive tread does is dig. Without aggressive tread you just spin and are easier to get unstuck. Any "open shoulder" traction tire won't give much more bite than a closed shoulder tread but will chop out much much quicker.

 

[javajoe79]

Fortunately, I live close to the militarytires.ca guys, so, getting newer humvee tires (between 1 to 6 years old) is not much of an issue. I do worry about long-term availability though. My understanding is the US nat'l guards will always use humvees, and the humvee will always have an ambulance role as the current JLTV replacement is too heavy or something... But still, I worry about if I need a new one while on the road.

That said, I'm yet to find someone who sells 20" tires newer than 8 years old here in Canada, and all the surplus ones are nearing 10 years old. I assume the same rules still applies; don't run 10+ year old tires regardless of the vehicle they're going on, if it goes highway speeds? As far as military tires go, humvee tires are a lot easier to find.

Using 17's would probably be ideal. But, I don't know of any in the 37"+ range on anything smaller than 20" wheels, that have a load rating of 3900lbs or greater, which is really the bare minimum for my rear axle, unless I go duals. If I could find some, that'd fix my problems. What are you planning on running? I do worry about running LT tires on a rig as big as mine. If I go duals with LT tires 37" or larger, it seems expensive and at that point it'd be cheaper to get 20" rims + military surplus 11R20's (but I haven't seen any commercially available steel ones for 20" - no one seems to make super single wheels in Canada, and shipping + exchange for 1stAttacks is pricey. The 20" tires seem a tad too heavy.

I could buy cheapo surplus 22.5" wheels for $70 ea. and 11R22.5 truck tires, run as duals (new, they're the same price as the used 11R20 military tires I've been able to find). The advantage of 22.5" rims is obviously widespread tire availability and durability. The price of 8 to 10 lug adapters is ridiculous though. I also worry about rocks pinching between both sidewalls of any dual rear setup, and blowing both tires.

I assume you went through similar thoughts with your rig? What's making you pull the trigger on what I'd assume are LT tires in 17"?

I'm not locked in yet but either way I will be building my own wheels. I also don't need the weight rating that you do.

 

[javajoe79]

I started looking at 20" options. Plenty of tires in the 37" with a high load rating. Then I see the 20" military 2 piece wheels. I can re center those like I did with the humvee wheels I have currently. Maybe that can work for you? I can draw the centers and have them laser cut.

10 Lug 2 Piece Tubeless Style Super Single Rim / Wheel M939 M809 fmtv lmtv

10-Lug 2-Piece Super Single Rim, / Wheel For M939, M939A1, M54, M809, M939A1, M939A2 Series 5-Ton Trucks LMTV / FMTV 2 1/2 and 5-Ton Trucks and M1082 and Variant Trailers

www.easternsurplus.net

https://www.discounttiredirect.com/buy-tires/nitto-ridge-grappler/p/41798

 

[baipin]

I started looking at 20" options. Plenty of tires in the 37" with a high load rating. Then I see the 20" military 2 piece wheels. I can re center those like I did with the humvee wheels I have currently. Maybe that can work for you? I can draw the centers and have them laser cut.

10 Lug 2 Piece Tubeless Style Super Single Rim / Wheel M939 M809 fmtv lmtv

10-Lug 2-Piece Super Single Rim, / Wheel For M939, M939A1, M54, M809, M939A1, M939A2 Series 5-Ton Trucks LMTV / FMTV 2 1/2 and 5-Ton Trucks and M1082 and Variant Trailers

www.easternsurplus.net

https://www.discounttiredirect.com/buy-tires/nitto-ridge-grappler/p/41798

Hmmm, this is promising! Some of the other wheels I had looked at were too heavy. The ones you're linking the same as these, I think: https://militarytires.ca/product/20x10-titan-5-ton-wheel/
The 11R20 Michelin XL's I'd consider putting on them would bring the weight per wheel/tire assembly to 250lbs. Think that's manageable for a Dana 60 front axle? This would actually be cheaper than the Humvee tire option, adapter price notwithstanding, which was previously the least expensive option by a huge margin. EDIT: With Hutchinsons I'm looking at 190lbs per wheel/tire.

I expect that the typical truck tire retailers would have 20" tires in stock eh? If I had a blowout on my spare somewhere in North America, I could get a new one from them relatively easily?

How much would you expect the adapters to cost? The best price I've found is from Western Canadian Rockwell at $190ea.

 

[javajoe79]

Hmmm, this is promising! Some of the other wheels I had looked at were too heavy. The ones you're linking the same as these, I think: https://militarytires.ca/product/20x10-titan-5-ton-wheel/
The 11R20 Michelin XL's I'd consider putting on them would bring the weight per wheel/tire assembly to 250lbs. Think that's manageable for a Dana 60 front axle? This would actually be cheaper than the Humvee tire option, adapter price notwithstanding, which was previously the least expensive option by a huge margin. EDIT: With Hutchinsons I'm looking at 190lbs per wheel/tire.

I expect that the typical truck tire retailers would have 20" tires in stock eh? If I had a blowout on my spare somewhere in North America, I could get a new one from them relatively easily?

How much would you expect the adapters to cost? The best price I've found is from Western Canadian Rockwell at $190ea.

Those wheels are similar. The ones I posted, the center is part of the inner half of the wheel. That would allow the most amount of offset if needed. Not sure about that weight with a D60.

There are a good amount of options for tires that would mount to that wheel. 37" and up and you would still have a decent sidewall.

Not sure on adapters. I am planning on cutting out the centers and welding in different centers so no adapters will be needed.

 

[tatanka48]

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"

 

[shortbus4x4]

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.