The 5-12 front tyres on my 1301d are badly rotted and need replacing. They've always seemed rather narrow to me, the rims are all scratched up because there's no tyre overhang of the rim like on most wheels, which set me thinking - will 6 -12 tyres fit ok on these rims and if so does the extra bit of width get in the way of anything?
Will 6-12 tyres fit on 5-12 front rims ok?
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284 International
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I don't know for certain, but I think they should fit. They have a larger diameter than the 5-12 tires, though, and will yield a different ratio between the front and rear axles. I know that is not recommended, but do not know how long it would take to show up as a serious problem. I would not do it on my machine, for what it is worth.
oldgrayfellow
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Its best to get the diameter or rolling circumference of the tires -- (these are sometimes listed on websites for new tires, otherwise it would have to be measured) and then compare those for the front and rear tires. Other things to take into account are (as you mentioned) the reduced actual diameter due to wear of tires you may have on one end of the tractor vs. new ones on the other. Further, the spec. or measured diameter of a new tire lying on a tire store floor may or may not be the same as the actual inflated diameter when its mounted.
But i have often wondered about the permissible limit of difference from the "stock" ratio between the front and rear...
As many on this board have pointed out though, 4wd really only needs to be used under ground conditions where there is some slippage or "give". Under these kind of slippage conditions, there is less of an issue with improper ratios, and if you only use 4wd under these conditions you should be OK. However, the correct ratio really should be observed because you never know when someone (even one's self) may forget to disengage the 4wd for an extended period...
But i have often wondered about the permissible limit of difference from the "stock" ratio between the front and rear...
As many on this board have pointed out though, 4wd really only needs to be used under ground conditions where there is some slippage or "give". Under these kind of slippage conditions, there is less of an issue with improper ratios, and if you only use 4wd under these conditions you should be OK. However, the correct ratio really should be observed because you never know when someone (even one's self) may forget to disengage the 4wd for an extended period...
They will fit I am sure however the gear ratio bias ft/rr is a big consideration as has been mentioned one size up is not a huge jump though but do the math anyway to be sure. (a +3.45% ratio ft-rr is what I seem to remember mine being as far as stock tire dia)
These are MFWD meaning as you know mechanical front wheel drive so there is no differential separating the front axle to rear axle like true 4wd. It is simply a pto drive off the transmission with a driveshaft to front axle and therefore nothing is perfect in the tire to gear ratio equation overall just acceptable.
fwtw I recently changed my front tire size to 8x16 US spec AG tires from (worn) 7x16 rice tires to match new rear US spec AG tires that were slightly oversized by 1 1/2" circumference and it worked just fine they have a way better load range for loader work also a plus. Keeping in mind 4wd is meant for loose or slippery surfaces anyway tire slippage is mandatory on all these regardless what the ideal tire size is my .002 ymmv as always try at own risk
edit: wanted to add that I load my tractor on the trailer w/o ramps I simply drive up to the back and drive up in 4wd. with the new (slightly larger dia) tires it drives up like it wants to load up rather than before I felt like I was pushing it to drive over the tail end simply an observation....
These are MFWD meaning as you know mechanical front wheel drive so there is no differential separating the front axle to rear axle like true 4wd. It is simply a pto drive off the transmission with a driveshaft to front axle and therefore nothing is perfect in the tire to gear ratio equation overall just acceptable.
fwtw I recently changed my front tire size to 8x16 US spec AG tires from (worn) 7x16 rice tires to match new rear US spec AG tires that were slightly oversized by 1 1/2" circumference and it worked just fine they have a way better load range for loader work also a plus. Keeping in mind 4wd is meant for loose or slippery surfaces anyway tire slippage is mandatory on all these regardless what the ideal tire size is my .002 ymmv as always try at own risk
edit: wanted to add that I load my tractor on the trailer w/o ramps I simply drive up to the back and drive up in 4wd. with the new (slightly larger dia) tires it drives up like it wants to load up rather than before I felt like I was pushing it to drive over the tail end simply an observation....
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oldgrayfellow
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Guess if someone really wanted to get exact information they could put the tractor up on blocks, put a narrow piece of tape or etc at the bottom dead center of each front and rear tire sidewall. Line up stationary markers (block of wood on the floor, etc) with the pieces of tape, and run the tractor in 4wd lowest gear until the rear wheel makes one complete revolution. Then you could see and measure the difference in rolling circumference (+/-) that the gearing gave between the rear and front tires.
From the difference, you could know what circumference of front tire would give you a perfect match. And from that matching circumference you could mathematically determine the exact diameter for the correct front tire. (Or vise-versa if you wanted to get new back tires to match the fronts.)
From the difference, you could know what circumference of front tire would give you a perfect match. And from that matching circumference you could mathematically determine the exact diameter for the correct front tire. (Or vise-versa if you wanted to get new back tires to match the fronts.)
284 International
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I have had to calibrate speedometers for actual tire circumference. I put a drop of water or White-out (but oil or whatever else would work, too) on the center of the tire, then roll until I have two marks (More is better; I'm usually able to get three on my motorcycles) and then just measure between the center of the marks. It is easy to get very precise, rolling dimensions this way. If one needed to do it in soft soil the tape idea would be better, and then measure between the centers of the tape mark in the imprinted soil.
In this case, I'm pretty sure the tire size will just be wrong. The 6-12 is basically 2 inches taller than the 5-12, so has more than 6" difference in the circumference. I'm sure you could get away with running it in soft stuff, but I just don't like the idea of stressing the front axles any more than they already suffer.
Put like that I see what you mean, 6 inches is a big difference. I was originally thinking the tyre would just be a little wider but of course they're proportionally taller as well. Looking at the prices the 6-12's are also quite a bit more money... I think I'll forget it and just buy some new 5-12's. Thanks for all your advice anyway.
I agree with 284's math if those are 2" taller yes that is considerable more roll out and I would not do it unless the rears were the equivalent oversize.
I got lucky my new mismatched tires came out correctly actually better than they were when I bought the tractor. My tires were no where near that far off though 1/2" to 1" difference in circumference most at the final figure if I remember right?
I got lucky my new mismatched tires came out correctly actually better than they were when I bought the tractor. My tires were no where near that far off though 1/2" to 1" difference in circumference most at the final figure if I remember right?
