Military Trucks - Single vs Dual Rear Wheels

[JA Boomer]

Over the past decades militaries seem to have been going back and forth between single and dual wheels on the real axles of military logistics trucks.

Does anyone have experience with the advantages/disadvantages between the single and dual rear tires? From what I have read, singles provide more traction in mud/snow/ice if you get stuck, but dual wheels are less likely to get stuck in the first place because the lower ground pressure allows them to float better in soft ground.

Currently military trucks seem to be favoring the singles, which the exception of recovery trucks which have dual rears, probably because they're doing a lot of towing.

 

[Albany Rifles]

Most trucks now have tire pressurization systems. This allows the operators to adjust the tire pressure depending on the travel conditions. This also allows for greater tractions as you mentioned. Also suspension systems are becoming more sophisticated. This precludes the need for dual wheels. The number of axles also determines the amount of cargo one can carry.

In the US FMTV series the frame is the same but the bed is extended and an extra axle is added to the 2.5 ton to make the 5 ton.



NOTE: When you see 2 1/2 ton or 5 ton, that denotes the amount of cargo the vehicle can carry across country. In reality, on paved roads the payload allowance is almost doubled....so a 2.5 ton can be used as a 5 ton in a pinch.

 

[JA Boomer]

That all makes very good sense. Is there a reason that recovery/wrecker versions perform better with dual rear wheels? They are the only ones I'm finding that are currently being produced with dual wheels, such as the Navistar MaxxPro:

 

[bfng3569]

tire width seems to quite a bit more on current vehicles vs older vehicles too.

on recovery vehicles I would think (no basis of fact here) that stability and traction as well as lowering/spreading out the ground pressure for recovery on soft terrain would be helpful.

 

[Guest]

Most trucks now have tire pressurization systems. This allows the operators to adjust the tire pressure depending on the travel conditions. This also allows for greater tractions as you mentioned. Also suspension systems are becoming more sophisticated. This precludes the need for dual wheels. The number of axles also determines the amount of cargo one can carry.

In the US FMTV series the frame is the same but the bed is extended and an extra axle is added to the 2.5 ton to make the 5 ton.

View attachment 46649View attachment 46650

NOTE: When you see 2 1/2 ton or 5 ton, that denotes the amount of cargo the vehicle can carry across country. In reality, on paved roads the payload allowance is almost doubled....so a 2.5 ton can be used as a 5 ton in a pinch.

Most tactical trucks are 4x4 (or all-wheel drive). It seems that a single tire performs better in the mud. If an “inside” tire would blowout it would take more time to change the tire than when only one single tire would blowout. Tire pressure is easier to maintain/service, and central tire inflation is easier to accomplish. Singles could have less inventory of tires, less fuel consumption, less own vehicle weight.

Manuel | Manager @ driveway repair fayetteville ar

 

[Tankersteve]

I wouldn't base too much design theory on MRAP-derivative vehicles. They were COTS, and not necessarily optimized for military use. For instance, many/most commercial wreckers have dual wheel rear axles. However, all purpose-built U.S. military wreckers are single wheel. The Navistar MRAP was designed using a lot of COTS components, and the wrecker is likely derived from a commercial wrecker design.

Another problem with dual axles is the tendency to get rocks and debris caught between the wheels. One can set up a 'picker' that forks out any jammed in debris, but ultimately, one big wheel is more efficient.

Tankersteve