Do liquid fill tire expand?

[MHarryE]

Tires do grow. The Tire and Rim Association specifies maximum grown dimensions for each size. Growing is due to use, not due to being filled. When they come out of vulcanizing, they have a "green" tire size. As the tire flexes, especially in the first hours, the cords and rubber find an equilibrium which, due to air pressure, results in a larger tire than when delivered. On the large combine and tractor tires with which I am most familiar, growth is significant. I am not sure what it would be on a small tractor like yours - you mentioned as much as 3/4 inch and that would be normal for a 30.5 x 32 combine tire. We've experienced more than that. Tires should be supported off the ground when filled. That is how we factory fill and through experience, I found that if they tried short cutting the operation, letting air out to just a few psi before pumping in fluid, a high percentage had fluid streaks down the tires, unacceptable for a dealer to find when the machines were delivered.

 

[Egon]

Try uping the air pressure to take the side bulge out of the tire.

 

[Jsandy]

No pics yet but I did take some measurements. The Tires are 16.9-24 6PR R4 TI. Based on what I've read the tire sectional width is 16.9". Measured center of the left tire to center of the right tire the tire tread width is just shy of 59" (according to the owners manual this corresponds to the wheels being mounted in the 4th position out of 8. Just where you'd expect the factory to mount them). When I measured the sectional width just now, the left rear tire is 18.25" and the right is 18.75". If those are accurate then that is my problem and the tires did expand. To measure them I took two pieces of 24x24" plywood and stood them on edge on each side of the tires, then took 2 large framing squares to make sure that I was measuring two parallel surfaces and measured between them.
The owners manual indicates that if the tires are mounted in the 5th position, the rear tire tread dimension opens up to 63" (6th position will open it up to 67"). I'll take the pictures today but I think the solution to my problem is going to be to remount the wheels in a wider position. I'll try increasing the tire pressure just to see if that takes up any slack (max is 26 psi) but I don't expect that to help.
I probably would never have noticed except for the 485A backhoe's unique attachment.

 

[Navasot]

I expect the added air to help

 

[Jsandy]

Ran the air up to 26 psi (max per owners manual). No help. I took pictures and will get them up when I figure out how to post pix to this site. If anyone wants a better idea of what I'm trying to do, here is a link to a video of how to detach and hook up a 485A backhoe https://www.muttonpower.com/t-how-to-install-and-remove-a-john-deere-485a-backhoe.aspx Note the amount of room that he has to install and remove the pins. To be clear, the 485A frame is in 2 parts. One part is attached to the tractor frame and is designed to stay there (doesn't interfere with the 3 pt hitch or attachments) The second part is the backhoe itself on a ladder frame. You remove your top link (it gets in the way) Attach a guide bar onto your lift arms and back into the backhoe until the guide bar engages a notch in the frame. Lift the backhoe with the 3 pt hitch to its highest point then lower the 3 pt hitch and the backhoe frame engages the frame attached to the tractor. Ideally the holes that the pins go through at the attachment point of the backhoe frame and the frame attached to the tractor line up and you slide the pins in from the outside (always takes some lifting and dropping to get the holes lined up, I'll guarantee that they didn't do the video in one take and that they edited the heck out of it). Unfortunately, since adding the ballast to the tires there is not enough room between the tires and the frame to install the pins.
Just for the heck of it, while I was out just now, I was able to get everything lined up and insert the pins from inside. The pins are not tapered so that they can only go in one way. Other than John Deere saying that the pins go in from the outside, is there any reason anyone can see that they shouldn't go in from the inside?

 

[Navasot]

It looks like he had about half a foot of clearance from the tires. Your saying they expanded that much? or was this on a different tractor?

 

[dusty3030]

Looks like to me inside would be fine.

 

[dusty3030]

It looks like he had about half a foot of clearance from the tires. Your saying they expanded that much? or was this on a different tractor?

Tractor in that video had the rears set to the widest position.

 

[Jsandy]

This is the right side



This is the left side




This is the left side with the pin inserted from the inside



This is a closeup of the right side with the pin inserted from inside

 

[dusty3030]

Should be fine, just watch if you get in some mud because those lynch pins have a habit of disappearing, other wise I'd say rock on.
Might make sure you have some spares in your toolbox.