Tire installation with mis-matched tread depths

[LuckyChow]

Over the winter I picked up some tires that were take-off's from retired buses at a nearby transit system.  I want to get a set installed on the rear of my bus in the next couple weeks.  Unfortunately, the tread depth variance between all of them is larger than I feel comfortable with, especially when it comes to mating them as dual sets.   I'd appreciate some recommendations from others on the board about how you'd handle this problem. 

Here's what I've got:

A total of five Michelin 305/R85  22.5 XZU 3.  All these tires are the same age, 3 years old.

Tread depth
2 tires – 12/32
1 tire – 18/32
2 tires – 26/32

My concerns are that putting two mismatched tires on one side (as a pair of duals) will cause the taller tire to heat up more.  In addition, installing mismatched pairs on opposite sides of the axle will cause the diff. to work harder, not to mention potentially setting off the brake fault sensor light as the anti-lock computer is watching to make sure both sides rotate equally (or within the allowed variance). 

One thought is to have two of the tires trued and cut down the tread depth.  This would waste a lot of tire, but on the other hand, they'll age out before they wear out anyway.    I'd appreciate your recommendations.

[daddyoften]

As much as it sounds right it's actually backwards, the shorter tire is the one that will heat up and pop! It's because of the turning radius of the smaller tire has to turn faster and it "skips".  I would never run different tires on the same dual. At the same time you are right about the different sizes causing the diff undo stress. I guess your idea of truing them up might be the best way to go.
But that's just my opinion....
Eric

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[Jim Eh.]

Ditto on the tire wear process. My vote would be shaving the tires to match them. Ask around for a retreading shop, they should be able to help you out.

[HB of CJ]

Yep ... shaving them comes to mind.  The shop doing such can also do a detailed inspection, looking for the possible side wall damage from transit service.  HB

[Aaron]

You might for grins take a cloth tape measure and measure the outside of the tires and see how close in size they really are,there may be a slight difference

[buswarrior]

Pair 'em up and run 'em.

Duel pairs need to be the same diameter, as noted.

Side to side, using the same tires, no issue for a busnut.

The differential? How many inches difference between the two pairs in a 495 revolution mile? How many inches does the diff deal with in the few feet of turning a corner? That's it's job.

Save cash, next topic.

Happy coaching!
buswarrior

[Lin]

I'd go with BW on this. You have two sets with equal tread wear, so a set on each side duals should be okay.  I had to replace a couple of tires some years back, so I have duals from one manufacturer on one side and from another on the other with no problems. There is no way those tires are exactly the same diameter.  My TPR does not show anything odd from side to side, nor is there any strange pattern wear I can see.

[Jon]

I think everyone's imagination is running wild. While conceptually I agree in a perfect world tires should be matched when running on the drive axle, in the real world when a trucker gets a flat or blowout, the tire company comes with a tire, slaps it on the trucker is back on the road. There is no way the tire guy shows up with three or four tires of different sizes to match them up with the remaining tire.

[gumpy]

Ditto. Put the two pairs on as paired and go have fun. 

The differential doesn't turn the same rate on both sides. That's kinda where they got the name.

[LuckyChow]

I appreciate it guys.  Earlier today I checked around for someone to do truing and pretty much struck out.  One shop had their truing guy fall off a ladder and will be out for at least 6 weeks.  No one else there can do it.  Another place can't do it on buses because they are too low.  A third said they had to swap each tire to the front of the bus so they could get at it.  This is not exactly what I had in mind.

I think BW has the right idea.  So, that's what I'm gonna do.  I appreciate all the comments.

[TomC]

Also-you do realize those are 55mph tires? Very stiff with sidewall reinforcing. To combat the harder ride, make sure you weigh the bus by axle and run the correct tire pressure according to the tire inflation guide. Running the maximum listed on the tire will just make the bus ride like a fork lift.

Size the tires to be the same on the dual side. Ideally you want to have all four the same size, but different side to side will cause the spider gears to work some-but then again-isn't that what they're for? Good Luck, TomC

[eagle19952]

Also-you do realize those are 55mph tires?

how do you determine this from the data offered ?

[LuckyChow]

Actually these aren't the Metro Miler tire commonly used in transit systems.  The Metro Miler is a 55 mph tire.  These are regular Michelin tires, not transit specific.  Michelin rates this tire as a 65 mph tire.  They have a coach model also, which is rated at 75 mph. 

[chessie4905]

http://www.michelintruck.com/tires-and-retreads/selector/#!/info/xzu3

[robertglines1]

In a perfect world the pairs would be within 3/4 inch circumference for the 2 individual tires.  FWIW   Bob