Choose tires wisely.

Dear Half-Mast,

I was about to change some tires on an M984E1 HEMTT wrecker when I noticed that we had different tire brands in stock. The tires are all the same size, but they have different tread patterns.

What's the scoop on mixing and matching different brand tires on the same vehicle?

SFC S.J.S.

Dear Sergeant S.J.S.,

There are three different tires approved for use on HEMTT vehicles. Two of them work well with each other, but the other one is a loner. Here are the details:

* When you order a replacement tire using NSN 2610-01-126-1576, you'll get either a Michelin XL (16.00R20, load range J) or a Goodyear AT2A (16.00R20, load range M).

Both tires can be used on the same truck without damage to the tires or the truck. It's a common practice to use all the same tires on a single axle, but it's not necessary. Both tires were tested together and are compatible on the same axle.

Here's the word from Para 2-7 of TM 9-2610-200-14. Care, Maintenance, Repair, and Inspection of Pneumatic Tires and Inner Tubes: "Minor variations of tread designs, as encountered from one manufacturer to another, may be used providing the sizes and tire constructions (bias or radial) are compatible."

* There is another NSN shown in the HEMTT parts TM. NSN 2610-01-334-2694 brings a Michelin XZL (16.00R20, load range M) that can be used on the truck only in a full set of eight tires. It cannot be mixed with the other tires.

Note that the XZL is used on the M1070 heavy equipment transporter and the Ml074/M1075 palletized loading system tractor. Just because the XZL can be used on the HEMTT does not mean that the XL or AT2A can be used on the HET or PLS. They cannot! The XL is not large enough for either vehicle, and the AT2A did not pass the use test for either truck.

* All three tires have non-directional tread, so it does not matter how they are mounted on the wheels. The tread can point forward or backward, although the tread on any XL tires used should point in the same direction.

* Some or all of these tires may rub against the HEMTT's front axle equalizer beam during a hard left or hard right turn. Eyeball the beam for evidence of rubbing. There must be at least 1 inch of clearance between the tread and the beam when the wheel is turned as far as possible to the left and right.

If you find evidence of rubbing, report it. Your DS shop will adjust the steering stop bolts to get the correct 1 inch of clearance.

* The Michelin XL tire should never be mounted to a bolt-together wheel. The XL requires an inner tube and inner tubes are not safe when used with bolt-together wheels. You can mount the Goodyear AT2A on a bolt-together wheel as long as you don't use an inner tube.

Half-Mast