OrangeKid - You're asking good questions, but perhaps the wrong ones.
Tipper's post is good. And review Denny A's FAQ on weight.
As Tipper notes, the Goodyear 14" Marathons are rated at 1870 pounds each. IF - and it's a big IF - the TM is loaded equally side-to-side, then the tires can support a total weight of 3740 pounds. RockyMtnRay has commented several times about the difficulty of loading equally side-to-side. The biggest problem is that the water tanks are all on one side, and water is heavy.
But please note! The axle can support only 3500 pounds. TIRES ARE NOT THE LIMITING FACTOR!
You can put 10,000 pound tractor tires on your TM, the axle will still limit you to 3500 pounds.
I weighed my 2720SL, ready for the road. At the moment it was weighed, that meant:
- No fresh water
- No gray water
- No black water
- Full propane
- Factory options: A/C, spare tire, awning, TV antenna.
- Clothes
- No food
- Microwave
- Tools
The TM was hooked to the tow vehicle, spring bars up in ready-to-travel position, so I was measuring the actual weight on the axles and tires.
The weight was 3340 pounds.
Road-ready weights up to 3700 pounds have, in fact, been reported. Scary. Pay attention to what and how you load. Sorry, but tricking out the tires won't get you around the limit.
Just my 2 cents worth.
Bill