M7040 How wide can front tires go?

KB7722 · Apr 9, 2018

CobyRupert said:
Many say that front tire width doesn't make tractor more stable, unless front axle has pivoted to the point it's hitting the stops; and if that has happened you've probably got other troubles (like rear tire has lifted) and it's probably too late.

There's also pros and cons of front and rear tires following same track.

p.s. I never understood how dish in/out puts more strain on the axle. The length of the axle to its connection point on rim is still the same. The weight the axle experiences is still the same, it's seems that just the "lever" (i.e. the offset of the rim's 'dish') is being applied to the axle in the opposite direction. That is, when dish is out, the top of the hub is in compression, the bottom is being pulled away from the axle. When dish is in, the "lever" action torque of this offset is still the same, it's just that the top of the hub is being pulled away and the bottom is in compression. Why is this thinking wrong?

It puts more stress on the king pin (for lack of better words) bearings. These are the bearing that front tires rotate about when steering. You increase the moment arm enormously by dishing the wheels out. It's like adding a cheater bar to a ratchet.

rScotty · Apr 10, 2018

KB7722 said:
It puts more stress on the king pin (for lack of better words) bearings. These are the bearing that front tires rotate about when steering. You increase the moment arm enormously by dishing the wheels out. It's like adding a cheater bar to a ratchet.

That's the way I see it too.
rScotty

JWR · Apr 10, 2018

I have a little different take on the front tire spacing concerns. The cheater bar analogy is a good one but I think more so on the spindle bearings. All other things equal, the force on each side, centered on the tread line, is half the weight on the front axle overall. On a 7040 that's probably around 2000lbs between the two fronts. A bunch more with a heavy FEL loaded. Could be on the order of nearly 2000lbs each side. That force is applied over some lever length going back to the front spindle bearings first before it gets to the "king pin" left/right steering pivots. You probably increase that lever by 4 or 5 inches by dishing the wheels outward. That may approx double the lever length to the spindle bearings. I view the cast spindle holder and bearings in it as the weak point, not the "king pin." So the question comes down to "how much risk versus benefit is there in ~ doubling the leveraged force onto those bearings and the housing containing them?" I agree with what I think I heard from others -- it ain't worth it. Esp if you intend rather large FEL loading. And I agree there is little/no benefit for rollover stability by widening the fronts.

That said, get those rear tires out as wide as you possibly can, given other constraints! They are your rollover stability. I like to run the inner edges of my front tires even with the inner edges of my rear tires but you have a lot of variables to deal with. If you cannot get the rear tires out that far, I'd add rear wheel spacers.

Rmart30 · Apr 10, 2018

I would like to have had the option for a wider front axle on my L4600 as I run my rears all the way out. I would rather have the fronts and rears running more closely in line than they do now.

repete · Apr 10, 2018

I have replaced both bevel gear housings due to hairline cracks and numerous outer wheel bearings on my L2550 while in the "wide" position. I have never had an issue since switching back to the "narrow" position which centers the wheel over the bearings and more in line with the housing cover.

My front axle stays narrow even if it is probably 10% less stable on a side hill.

Gregg

Farmer495 · Apr 12, 2018

I test drove an M5040 with loader that had the wheels dished out like that, first sharp turn I made in the flat dealer parking lot the tires hit the loader mounts........