Tire Selection Can I put slightly wider tires on the stock rims?

[arrow]

True. But a matched pair of oversized tires on one axle will be problematic on a 4WD Tractor. That is my point and it is a valid one.

Yes and no. Depends on the manufacturers tolerance ratio to roll out comparison which can be anywhere from 2-5%. Less problematic of putting slightly larger tires on rears than fronts. A more definitive answer could be obtained by comparing first tire diameter of tires in question then multiplying that diameter times pi and then by a median 97% to get roll out for one revolution. Take the percentage of the increase between the two and see if it falls within manufacturers ratio parameters.

 

[RickB]

Yes and no. Depends on the manufacturers tolerance ratio to roll out comparison which can be anywhere from 2-5%. Less problematic of putting slightly larger tires on rears than fronts. A more definitive answer could be obtained by comparing first tire diameter of tires in question then multiplying that diameter times pi and then by a median 97% to get roll out for one revolution. Take the percentage of the increase between the two and see if it falls within manufacturers ratio parameters.

Blah blah blah. FYI it’s called the lead/lag ratio, and reputable tire manufacturers have dimensional data published online so there’s no need for the string and calculator. Larger rears will shift the ratio faster than any other change. And because the OP hasn’t been back, and we don’t even know if the tractor in question is 4WD, I’m done here.

 

[npalen]

Might be able to go with slightly oversized tires on the front as well to compensate.

 

[Texasmark]

True. But a matched pair of oversized tires on one axle will be problematic on a 4WD Tractor. That is my point and it is a valid one.

Oversized in circumference, aka (outer diameter of the tire/2)squared x pi, surely, but has nothing to do with the inner diameter nor the width. And to be more exact in matching fronts to rears, the "rolling" circumference of the tire which is not the same as the "static" aired up circumference.

 

[arrow]

Might be able to go with slightly oversized tires on the front as well to compensate.

If the difference in tire diameter and thus circumference is negligible between these two tire sizes, he may simply be able to put the larger rears on and get away with it. If not, he can always air down the rears and air up the fronts to make up a small difference. As long as the rears are not pushing the fronts and binding the tractor, the op will be fine.

 

[arrow]

Blah blah blah. FYI it’s called the lead/lag ratio, and reputable tire manufacturers have dimensional data published online so there’s no need for the string and calculator. Larger rears will shift the ratio faster than any other change. And because the OP hasn’t been back, and we don’t even know if the tractor in question is 4WD, I’m done here.

What's with the "blah, blah blah? This is easy crap to do as it's 5th grade math. But hey, you can take your ball and go home with your generalizations which as with all "generalizations" can be valid...or not.
BTW, we know it's 4wd as it has a "D" after its model number and who cares if the op ever comes back as long as the "correct and accurate" information for anyone to see is given instead of "generalizations"

 

[CobyRupert]

The Op wants to go from 8.3" x 20" to 9.5" x 20".
How could that put "extra strain" on the drivetrain?
Isn't an 8.3" x 20" tire the same diameter the same as a 9.5" x 20" tire?

Just a guess, but if they bite more than a narrower tire that would otherwise spin, isn't that extra strain? Sort of like adding more weight for more traction.

 

[RickB]

Oversized in circumference, aka (outer diameter of the tire/2)squared x pi, surely, but has nothing to do with the inner diameter nor the width. And to be more exact in matching fronts to rears, the "rolling" circumference of the tire which is not the same as the "static" aired up circumference.

A 9.5” Tire will be taller than an 8.3” Tire of the same diameter. You can take that to the bank ,my friend.

 

[arrow]

Just a guess, but if they bite more than a narrower tire that would otherwise spin, isn't that extra strain? Sort of like adding more weight for more traction.

Sometimes. A narrower tire may actually have more bite in certain situations such as soft terrain where the wider tire may have more floatation. Ever see those old movies of model A cars going through foot deep mud with tires no thicker than a man's wrist? I think the poster may have meant more about screwing up the drive geometry with a larger tire and if a great enough difference, would certainly put more stress on the drive train

 

[Texasmark]

A 9.5 Tire will be taller than an 8.3 Tire of the same diameter. You can take that to the bank ,my friend.

Really. Since I have accumulated a pile of tires for my mowers, I may just do run some measurements. If I need to "eat Crow", I can do that.