1959 GMC Adventure Bus Build

[baipin]

So, I ended up finding MPT81's and MRAPs for practically a steal. I think I'll pul the trigger on 'em tomorrow. I'd prefer GSA's or Pirellis or something with better tread life than the MPT81's - their 25k miles is equal to the Humvee's - but I'm just happy to "upgrade" to 20" wheels and more options in the future (including 365/80R20, assuming a 35 spline Dana 70 front axle would survive that).

Here's a bit of a teaser of what the bus will look like if I go through with this plan... (with a 12" roof raise, too)!

 

[baipin]

For those curious, here's the third option and what I'm leaning towards right now: 11r22.5



The lack of 335/80R20 availability, plus the cost - even for tires that have nearly ages out, concerns me. If tread lifeof mpt81s is only 20k to 25k miles with these, as I've read to be the case, I'd be going through 4 sets every decade with how many miles I suspect I'll put in the bus. At $750 to $890 CAD per tire... That gets unreasonable, quickly.

11R22.5s can be had anywhere, are inexpensive, can use a runflat insert, and quality big lug on/offroad tires should last double to triple the MPT81s from what 6 folks in the tire business have said, so unless I'm missing something, I'll go with 11R22.5s. they also seem faster and less complicated to seat and unseat from a single piece rim, ironically, compared to multipiece 20"s.

Opinions would be appreciated!

 

[marret]

No expert, but what you say makes sense. One downside might be a less aggressive tread pattern if that is important.

 

[baipin]

No expert, but what you say makes sense. One downside might be a less aggressive tread pattern if that is important.

I do indeed want an aggressive tread. Here's one 11R22.5 example of the sort of tread design I'm after:



Two places - one who sold this model of tire and a similar Doublecoin one - both said they had drivers doing 60k to 80k miles (not kilometers) on them. Given I heard that number repeated by 5 or 6 different people, I'd assume it's an acceptable ballpark figure?

 

[marret]

Right, I would think that mileage is acceptable. The tire shown looks ok as far as tread pattern, but it doesn't have the shoulder lugs the others you showed so they may not be as good in mud. Don't know how they shed mud.

I run BFG KO2s which aren't great mud tires, but pretty good all terrain.

 

[baipin]

Right, I would think that mileage is acceptable. The tire shown looks ok as far as tread pattern, but it doesn't have the shoulder lugs the others you showed so they may not be as good in mud. Don't know how they shed mud.

I run BFG KO2s which aren't great mud tires, but pretty good all terrain.

I did not think of that - great point. I feel like the shoulder design... overall design, really... is similar to the XZL lugs. How does that fare in the mud?

 

[shortbus4x4]

11R22.5 tires are everywhere. I don't think you can go wrong. For ice and snow driving get them siped, I know it shortens the tread life some but it is well worth the extra traction.

 

[marret]

Agree about siping if you will need them for snow and ice amd also that tire size is common. Those tires have no real siping.



Not familiar with XZL, but the shoulders are more open, shoulder lugs angled, and Michelin says the tire is self cleaning.

 

[baipin]

11R22.5 tires are everywhere. I don't think you can go wrong. For ice and snow driving get them siped, I know it shortens the tread life some but it is well worth the extra traction.

Yeah, we have plenty of that up here, good call. Will be spending lots of time in Ontario, Quebec, and Vermont...

Think 11R22.5 is fine to run as a singled rear? The weight capacity is perfect for that, but how's the footprint with a relatively narrow tire? The Humvees and MPT81's are both 1.4" wider, for what it's worth.

 

[I play outside]

Siping and groove them yourself for a custom tire. That’s a super common tire. May be a wise choice.

 

[shortbus4x4]

Yeah, we have plenty of that up here, good call. Will be spending lots of time in Ontario, Quebec, and Vermont...

Think 11R22.5 is fine to run as a singled rear? The weight capacity is perfect for that, but how's the footprint with a relatively narrow tire? The Humvees and MPT81's are both 1.4" wider, for what it's worth.

Flotation is the only downfall but airing down some should help, of course 22.5 rims typically don't have any bead retention so you might have issues there depending on how low you go. Should have no problem running it as a single in the rear. Only question is are you planning on running custom rims to make your front and rear tracks match?

 

[86scotty]

Sweet build. You should name it McCandless.

 

[baipin]

Flotation is the only downfall but airing down some should help, of course 22.5 rims typically don't have any bead retention so you might have issues there depending on how low you go. Should have no problem running it as a single in the rear. Only question is are you planning on running custom rims to make your front and rear tracks match?

I'll be running these rims if I go with 11R22.5, I think:



With the 77" KP Chevy Dana 60 (well, Jana 76) WMS, and a typical 74" WMS with whatever beefier rear I choose (likely a Dana N175 or a Meritor/Rockwell 15,000lb axle), I suspect the front and rear will line up nicely. Still need to take exact measurements, though. Weight comes in at 235lbs with a tire. I think that's fine? I could always machine holes into the wheel face...

If I went with a 315/80R22.5 I'd do something similar, but with four 22.5x9 Alcoa float rims instead. Thing is, I can't find many deep lug tires in that size. The only suitable one for sale, locally, is the Westlake MD777. I don't exactly have great impressions of that brand though...

The tire I posted above has 1" deep lugs, this is 0.72", for what that's worth...

 

[baipin]

Thought y'all might want to see my new rear end. With this, I'll be ditching the Humvee wheels and solving my weight capacity issues...

Started by getting the parking brake off, to then get the yoke off, as I need a 1550 size. This was 1610 I believe and I don't need yet another Ujoint size on my rig...

Had to cut the drum off...

Everything literally crumbled apart soon as I touched the shoes. We're swimming in saltwater up here every winter...

For comparison sake, here's a D60 cover next to a D80.

...and next to this axle, lol.

I'm not certain, but I believe it's a 19060S. 15" ring gear lol. Unfortunately, it's open, but it's a 4.10 - a Detroit is available - this axle has the correct bolt pattern, not too large, and has the correct 71" WMS I need, and that combination isn't easy to find - and for the price it was, I'd be an idiot to pass it up.

 

[shortbus4x4]

Looks good. What will you do for the emergency brake now?