[JohannesG]

Hi

An old thread, but I like to share my experience on the topic of weight distribution, traction and 4wd.

I have had the opportunity to compare a standard tractor with MB trac pulling the exact same load. 

Tractor 1: Valmet 8050 with 600/65-R38 rear and 480/65-R28 front. 5 ton tractor, no extra weight.
Tractor 2: MB trac 1000 with 18,4-26 all around. 4,5 ton tractor, no extra weight.

We have some steep gravel roads and pulling a Rolland Rollforce 6118 manure spreader weighting somewhere around 17-18 tons there is a big difference in grip.

The Valmet pulls it without any visible loss of traction, however if you don't activate 4wd it won't steer as good.
The MB trac on the other hand fights to find traction even with 4wd and diff locks engaged, barely enough to get up the hill.

So, what it comes down to is surface area and the weight on that area. And even if the MB trac would have had 600 wide tires it still wouldn't pull as good due to the small diameter making the length of the contact area smaller.

Best regards
Johannes, Sweden