I have seen tandem singles on a few rigs and here were the thoughts behind them:
1. Lakes Fire Company, Medford Township, NJ - On an Imperial for flotation on soft ground.
2. Beech Mountain, NC - On an International Cargostar/Howe for improved braking on mountain roads.
3. Marshalls Creek, PA - On a Ford N/American for improved braking on mountain roads.
4. Saint Johns County, FL - On a Kenworth T-800/Pierce for flotation on soft ground.
5. USAF - On International Paystar 5000/KME P-18's for flotation on soft ground.
I would guess that it's more likely the braking ability on the Crested Butte rig.
1. Lakes Fire Company, Medford Township, NJ - On an Imperial for flotation on soft ground.
2. Beech Mountain, NC - On an International Cargostar/Howe for improved braking on mountain roads.
3. Marshalls Creek, PA - On a Ford N/American for improved braking on mountain roads.
4. Saint Johns County, FL - On a Kenworth T-800/Pierce for flotation on soft ground.
5. USAF - On International Paystar 5000/KME P-18's for flotation on soft ground.
I would guess that it's more likely the braking ability on the Crested Butte rig.