Tires not round--wobbling on pavement

[JackJ]

I've had my BX1870 for a month now, and while very happy with it overall, I've got one issue that's bugging me.

I regularly drive it 1/2 mile on my road to a friend's house, and when moving (relatively) fast on pavement, there's a very noticeable wobble. Seems like it's worse now than it was right after delivery, but I'm babying it less, so maybe I'm just driving it faster where the wobble is more noticeable.

The cause is clearly that the tires and/or wheels aren't perfectly round since the movement is in sync with the tire revolutions. In researching it, I'm seeing this talked about on other tractor forums, but not so much here. But it's apparently common. My old Ford didn't do it though, at least not very noticeably.

I've got OEM turfs, with Rimguard in the rears. Tires have the same psi--14 in back and 21 up front. (Manual says 17 up front, but my dealer recommends more when doing loader work--all the way up to 28.) I don't yet have a big torque wrench, but I've verified that all the mounting nuts are tight.

I think I may be getting a flat spot that's more pronounced on the left rear tire. I can also see that despite the same psi, my two rear tires have a slightly different shape, with the left having a more rounded tread and the right being just about flat. Seems like that's probably a manufacturer's inconsistency, and I think the tires must have come from two different molds since some of the minor markings on them are different. If that's all it is, I guess I'll learn to live with it. I'm curious if it would be the same without tire ballast, and if the ballast sloshing around might be part of the issue.

I don't have any jackstands, but I'm thinking about borrowing some and getting the tires off the ground so I can measure the runout of the rims and the tires. If the rims are slightly off, I'm wondering if a slight adjustment is possible by moving the rim a bit on the lugs. Right now, that's my only hope for a remedy. Not sure my dealer will agree that it's a problem that needs fixing, and it would probably cost me $200 for them to look at it, since I'm some distance away and they made it clear than even warranty work would still require me to pay transport costs.

Has anyone else addressed this issue? Or is it just the nature of most tractors and something I should learn to ignore? The wobble isn't horrendous, but near top speed it's not subtle, either. I'd like to fix it to whatever extent I can.

Maybe I'll try to capture it on video, though I suspect it will appear less significant than it feels.

Jack

 

[85Hokie]

Funny you mention this, I have taken my BX25D on several trips that require 1/2 mile drives to other places - all those occasions, I felt a "wobble" if you will, or a hop, kinda like a "gallop" of a horse. I have my tires filled, and I thought it might be the fluid getting sent around and making it hop......now I am not sure. Mine is on the left side. I have looked from the drivers seat and I cannot make out anything that looks unusual. I never notice it unless I am going as fast as possible!

 

[D2Cat]

I'd guess it is the fluid in the tires being forced to an outer spin then suspended there while turning, and the tire is out of balance.

 

[1970cs]

The mismatched tires turf tires are a common problem on the rears! They are matched at the supplier but once the get shipped they seem to get lost.

Your dealer needs to get you a matched set for the rear! This should throw off your loader bucket level by around 1/2-3/4"

As far as the gallop it is possible that one of the tires is out of round?

Pat

 

[ironpony]

First with my OCD I would definitely want a matched set. Then I would remove the tire rim combo, switch sides and retorque everything properly and see if this helps or changes where it is coming from. Who knows who installed them originally. Follow the tightening sequence to make sure it is seated properly on the hub. If nothing changes you could dismount/remount them different on the rim and see if this helps. As you stated running them raised in the air might show a bent rim, tire wobble or out of round condition.

 

[armylifer]

After I loaded my tires I noticed the same thing happen with my tractor. One thing that I did after this first happened was to make sure that I had the same amount of water in each tire. I did this by parking on a level driveway pad and got both rear wheel valve stems at exactly top center. Then I lowered the rear of the tractor and let out air in each tire until all air was out and just water was coming out. I did this with the valve core loose but not removed. After the air bled out and water started seeping out of both tires, I tightened the valve cores and put 18 lbs in each back tire. This helped but did not cure it all the way. Now when I am driving on pavement the first 150 feet or so, the tires still gallop but smooth out after that as long as I stay at a steady speed.

 

[trapperdrew]

I get a wobble on the road with my turf set on my bx2370, but none with my R4's on.

 

[hodge]

I've been around tractors all of my life, and experienced it with all of them. It isn't a Kubota thing. It's a bias ply tire, that sits a lot, with weight added to the interior, and these tires aren't balanced like a car tire.
Who knows how long your tractor sat on a lot, possibly without moving for long periods? They will get flat spots from sitting, and usually it clears up after running them some. My B7100 does it, but not all of the time, and it will do it after having run it for a while. I don't know of anything that you could do to correct it- it is a condition that seems to be natural to tractor tires.
Now, if you have a bent rim or axle, that is different. But, a wobble in the rubber- that is what it is.

 

[scdeerslayer]

I've experienced this but I've always thought it was from the tires compressing and just getting in a bouncing rhythm at a certain speed. Seems I can slow down a little and it goes away then speed up a little and it takes a while for the wobble to start back. Of course I'm only going a little over a mile on the pavement so I don't have much time to experience it. I'm sure liquid ballast contributes as well. I should find out soon, I had my new tractor on the road before the tires were filled with no wobble. The tires are filled now and I'll have it on the road soon so I'll see if there's a wobble.

My dealer actually came out and filled my tires. It was actually a pleasant surprise. I had been talking with one sales guy but he was with another customer when I went by there one time and I spoke to someone else and asked him about filling the tires (thinking on the off chance if they used Rimguard I might get it, but I doubt anyone near here sells it). He said something about they just used water/antifreeze and mentioned that he didn't know how much that cost, so I didn't bring it up anymore thinking I'd just do it myself instead of paying them to do it. The dealer had to come out a couple weeks after delivery to install a rear remote valve that was backordered and I bought all the stuff to fill the tires and was planning on doing it that weekend. Saturday at lunch time I get a call from the sales guy saying they had forgot to fill the tires and would come out and fill them the next week. Now I have plenty of antifreeze on hand for whenever I need to do a coolant change.

 

[tiredguy]

Hodge hit the nail on the head for tendency of the tires "flat spotting" being
bias ply and the materials used are actually the biggest culprit.

That said the first thing I will forewarn anyone attempting to determine whether or not their tire is "out of round" is that it can't be done with a cold tire. Nylon
is a super tough material used in making tires, bias ply specifically because it's
so strong. Nylon ( ask any old timer ) will flat spot from setting but changes with heat so that the warmer the tire gets from running it the smoother it will get.
40 years ago it wasn't uncommon at all for tire on a 3/4 ton or 1 ton truck to ride harshly for up to 10 miles, worse in the winter than summer nature of the
beast.

To check the roundness of the rims and possibly the tires because they will sag quickly due to the nylon in them, raise the tires off the ground blocking them with jack stands or solid wooden blocks ( never use cement blocks! ) so they can be rotated by hand. Using another object like a wooden block etc place it as close as you can to the tire/wheel assembly so that you can see
movement side to side and up and down as the tire is rotated around. An extra set of hands is best so that one person can rotate the assembly while the other is watching the "run out". The idea is to see how far the rim flange moves side to side or up and down so a "pointer" of some type be it a screwdriver stick etc set as close as possible to further be able to see how far it moves. A bent axle or rim flange on the axle is always a possibility and you may have to remove the tire assembly and check that too. Keep in mind that the deeper the tread the more pronounced that wobble or lope actually will be. R1's will be worse than R4's and turfs far less then both because they have no "lugs" that squirm or move more than the shallower tighter tread segments.

Liquid ballast should not change the feel if filled equally in both tires and the air pressure is set identical too. One exception would be if the ballast is water and as such frozen if experienced in the winter etc. That changes everything
and is never good.

I have R4's on my B3030 and would change them tomorrow if I could to so with the exact same diameter tires but can't because I've already altered the door height so it will go in and out of my garage door it barely clears now.
Turfs with the tighter tread ride so much smoother and I too have one of the rears that lopes quite a bit that I simply try and ignore. It's not a Cadillac so
one can't expect a tractor to ride like a car simply put. We're as spoiled today with the ride of our cars and trucks running on awesome round radial tires that have such tight tolerances to make everything so smooth. Suspension
on a tractor doesn't exist only tires for cushion and no springs shocks and rubber bushings to cushion the movement.
Al

 

[coachgeo]

Anther idea is to after they are warm draw some lines across the tire inside to outside, diagnal etc. in various areas on the tires and it's opposit. Drive again to see where the chalk wears off.

Could possibly splat in various places some chalk used for filling a carpenter's chalk line for same purpose. Maybe use sidewalk chalk to outline the splat to help see changes.