Hi Sevanje
Congratulations on your new Grillo G110, and welcome to the 2-wheel tractors forum
As I read your posts and saw your pictures, I felt confident that you are on a perfect track to get the most out of your new tractor. You have mounted larger wheels, increased the track width, and finally you have added wheel weights. These are all changes that will increase stability and tractive efficiency, and changes that are especially important when you are using your tractor for pulling.
As you perhaps are aware, using a tractor for pulling is the least efficient (but most used) way to utilise a tractor, as often only around 50-75 % of the engine power is transferred into pulling power when working in the field - and even less, if the tractor is not correctly ballasted. The most efficient power transfer is via the PTO, where you can expect around 95 % of the engine power to be available. - This of course doesn't help you much, if you want to use your tractor for pulling a cultivator, I know
I don't think that you have to worry to much about your gearbox not being up to the job - even with 130 mm spacers, the big diameter wheels and the wheel weights. These tractors are well build, and many of them will probably outlive most of us
If you take a look at this page from Earth Tools, you will see that Joel mentions the limit for wheel extensions to be 10'' on either side, as this is the maximum recommended by the tractor manufacturers:
Wheel Accessories - Earth Tools
With your 130 mm, you are only about halfway towards that limit, so no problem :thumbsup:
It is perhaps also useful to remember, that your wheel weights decreases the bending moment on your gearbox, as they sit on the outside of the wheels. On top of that, you seem to use your tractor with relative light implements, and they don't add much weight - and bending moment - to the tractor. If on the other hand, you would for instance connect a 85 cm Berta flail mower weighing 92 kg to your tractor like I do, you would basically add this weight to your tractor, when you press down on the handlebars to lift the mower off the ground. That puts a lot of stress on the axles and the gearbox, but again part of it is alleviated by the wheel weights. The wheel weights doesn't help when the tractor is used to pull or push hard though, and therefore the note written in bold letters in the above link is worth noticing! Maximum 8'' extensions when using such implements :thumbsup:
Looking at your picture where you are cultivating your potatoes, you don't seem to have any problems with flotation or compaction at all. Therefore you won't get better traction by adding duals to your tractor - except the extra traction due to the added weight, of course. For your kind of job, narrow tall wheels gives you a nimble tool that is ideal for hoeing potatoes and the like. Large diameter wheels have the added advantage, that they increase the length of the contact patch, giving you better traction than a smaller but wider tire would.
Adding weight to a tractor, is in most conditions a very efficient method of improving tractive performance - especially on loamy and sandy soils, like the ones you seem to have. One might sometimes wonder just how much wheel weight to add them? The rule of thumb is quiet simple and straight forward: As little as possible, but enough to reduce slip to a reasonable level.
What a reasonable level is, depends mostly on the type of soil that one is working on, but in most situations, a slip above around 20 % is not desirable. 12-15 % is in many situations an optimum value. Sadly, we don't have a gauge on our small tractors, that will show us what our slip percentage is. Looking at the ruts created by the tires, might give us a hint though. If the tread pattern left by the tire is fully "intact" showing no signs of slip at all, the tractor might be over ballasted, and might waste power and fuel, dragging unnecessary "dead weight" along. If on the other hand, the slip is clearly visible, and the tread pattern is "torn apart" in the rut, power that could have been used for traction, is lost as well. In this case, weights should be added, until the slip is hardly visible again.
All the best with your new tractor
Best regards
Jens
