B7200 new tyres and rims

[Paul Allwood]

The standard turf tyres on my B7200 are showing signs of age. The treads are not too bad but the sidewalls have loads of cracks. The standard tyres are:
- Front 20.5x8-10
- Rear 31x13.5-15

When I first bought the tractor a few months ago I knew the tyres weren't great, and I imagined I would rock up to a tyre shop and have a choice of tyres to replace them. Wrong. I can find rear tyres but they are expensive, but couldn't find front tyres.

I wanted something with more grip than turf tyres, but not as aggressive as ag tyres so I settled on skidsteer tyres. Also wanted a good load rating for the loader.

I've ended up with the following tyres:
- Front 23x8.5-12 (RC 68.3")
- Rear 12-16.5 (RC approx 98.9")

It's 4WD so the rolling circumference ratio matters - rear/front = 98.9/68.3 = 1.45. I think I've seen somewhere here that the spec for this tractor is 1.46.

These are both readily available skidsteer tyres here for $200 (rear) and $160 (front).

The next challenge is the rims. I may be able to buy them from Kubota if I sell the house, so I needed another option.

I found two good used 16.5x9.75 bobcat rims for the rear on Facebook marketplace and bought two new bare 12x7 rims for the front. These sizes match the new tyres.

On the rear I'll need to make an adaptor to go from the current hub to match the bobcat rims - this might also double as a wheel weight as I want to keep the tyre width about what it is now.

On the front I'll just need to make a centre to match the front hub and weld it into the bare rim, keeping the tyre centreline the same.

You can never have too many projects. When you get stuck on one there's always something else to work on.

 

[North Idaho Wolfman]

The standard turf tyres on my B7200 are showing signs of age. The treads are not too bad but the sidewalls have loads of cracks. The standard tyres are:
- Front 20.5x8-10
- Rear 31x13.5-15

When I first bought the tractor a few months ago I knew the tyres weren't great, and I imagined I would rock up to a tyre shop and have a choice of tyres to replace them. Wrong. I can find rear tyres but they are expensive, but couldn't find front tyres.

I wanted something with more grip than turf tyres, but not as aggressive as ag tyres so I settled on skidsteer tyres. Also wanted a good load rating for the loader.

I've ended up with the following tyres:
- Front 23x8.5-12 (RC 68.3")
- Rear 12-16.5 (RC approx 98.9")

It's 4WD so the rolling circumference ratio matters - rear/front = 98.9/68.3 = 1.45. I think I've seen somewhere here that the spec for this tractor is 1.46.

These are both readily available skidsteer tyres here for $200 (rear) and $160 (front).

The next challenge is the rims. I may be able to buy them from Kubota if I sell the house, so I needed another option.

I found two good used 16.5x9.75 bobcat rims for the rear on Facebook marketplace and bought two new bare 12x7 rims for the front. These sizes match the new tyres.

On the rear I'll need to make an adaptor to go from the current hub to match the bobcat rims - this might also double as a wheel weight as I want to keep the tyre width about what it is now.

On the front I'll just need to make a centre to match the front hub and weld it into the bare rim, keeping the tyre centreline the same.

You can never have too many projects. When you get stuck on one there's always something else to work on.

I could have given you a much cheaper and easier alternative.
Truck tires, they have the right sizes easily available, they have a lot of tread options.
I've done it, my first B7100 had truck tires on it, and still does.

 

[Paul Allwood]

I could have given you a much cheaper and easier alternative.
Truck tires, they have the right sizes easily available, they have a lot of tread options.
I've done it, my first B7100 had truck tires on it, and still does.

I did look and could find options for the back but couldn't find anything for the front. What have you used ?

 

[North Idaho Wolfman]

I did look and could find options for the back but couldn't find anything for the front. What have you used ?

ATV tires

 

[Paul Allwood]

ATV tires

I looked at ATV tyres, and gave up trying to find a good front/rear size ratio when I found the right ratio with the skidsteer tyres. And I liked the skidsteer tyres.

 

[D2Cat]

To modify your skid steer wheel to fit the Kubota can you cut out the enters and weld them in?

 

[Paul Allwood]

To modify your skid steer wheel to fit the Kubota can you cut out the enters and weld them in?

Thanks. That's definitely one option - might be easier than making up something like big wheel spacers that I was thinking about. I don't have these wheels yet so I'll wait until I have them here to decide.

 

[Paul Allwood]

I've made a start on adapting skid steer rims to fit the rear, and also fitting a better mount plate to a bare rim fire the front.

The standard Kubota rims that are on there now have plain holes over the wheel studs, and are secured by plain nuts and flat washers. Does anyone know why it's done this way rather than with tapered wheel nuts into matching countersunk holes ?

 

[North Idaho Wolfman]

I've made a start on adapting skid steer rims to fit the rear, and also fitting a better mount plate to a bare rim fire the front.

The standard Kubota rims that are on there now have plain holes over the wheel studs, and are secured by plain nuts and flat washers. Does anyone know why it's done this way rather than with tapered wheel nuts into matching countersunk holes ?

They are concentric rims, that's too say the center hole is the alignment point for the wheel, not the studs.
I'm pretty sure their thinking is that washers and flat nuts are better at holding a loads with rapidly changing forces on the rims.
Your not going to need any ballast weight with those monster inserts and rims.

When you get the rims and tires on the tractor, put it on a hard, flat surface, put it in 4wd, put it in neutral on the range, and try and manually push the tractor forwards.

 

[Paul Allwood]

They are concentric rims, that's too say the center hole is the alignment point for the wheel, not the studs.
I'm pretty sure their thinking is that washers and flat nuts are better at holding a loads with rapidly changing forces on the rims.
Your not going to need any ballast weight with those monster inserts and rims.

When you get the rims and tires on the tractor, put it on a hard, flat surface, put it in 4wd, put it in neutral on the range, and try and manually push the tractor forwards.

Fair enough, and thanks. The question was a bit of an afterthought as I've countersunk the holes already for tapered wheel nuts - the main reason was so that I didn't have to change the wheel studs to longer studs on the rear to suit the thicker (12mm) mounting plate. My guess is that if plain nuts and flat washers work with a rim thickness of about 5mm, the tapered nuts will probably work ok into 12mm plate.

I'll have a go at weighing the new rear wheel assemblies vs the existing. Will be interested to see just how much heavier they are. I'll still add liquid ballast to the rear tyres - I drilled holes for 2 tyre valves for this - one to let the water in and one (with the valve guts removed) to let the air out).

The spec's on the tyres I've bought show that the rolling circumference ratio should be a close match for the front:rear drive ratio, but it will be an interesting test to see how it rolls. I'll test it as you suggest on our cricket pitch - you can google to see what that is .

 

[Paul Allwood]

Some progress on the new front wheels today - one wheel fully welded both sides. The second one tacked. The centre plate is 10mm, the rim is 3mm.

All the real welders out there will notice that I'm not a welder, but I try. Looks better with a coat of paint - should look even better with some more paint and a little dirt.

 

[Paul Allwood]

I wanted to check how true the welded front wheels were running so I tried one on the wood lathe as the diameter was too big for the metal lathe. I'm wishing I could find the old front hub that had lost it's splines - I think it's under a ton of junk in the trailer.

It's located on a crown wheel mounting flange from an old LandCruiser diff. One of the two pieces on the tailstock sides is the old front splineless bevel gear. Two pieces sitting against each other at the tailstock isn't perfect, but the wheel seems to be running pretty true. I'll leave the next test for when I take them to get the tyres fitted.

I'm hoping it'll be good enough for the front of a tiny tractor at a max speed of about 12 km/h.

22 March 2026

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[Hugo Habicht]

I'm hoping it'll be good enough for the front of a tiny tractor at a max speed of about 12 km/h.

That runout looks about 10 times better compared to what I achieved straightening my bent rims. Those wheels will be perfect.

And my tractor gets to a top speed of an incredible 13km/h

 

[Paul Allwood]

That runout looks about 10 times better compared to what I achieved straightening my bent rims. Those wheels will be perfect.

And my tractor gets to a top speed of an incredible 13km/h

Thanks Hugo. 13 km/h - that's getting up there.

 

[Paul Allwood]

I welded the plate into the bare rim on the second front wheel this morning. Still not a welder, but I reckon it looks a little better than the first one.

24 March 2026

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[North Idaho Wolfman]

I welded the plate into the hub on the second front wheel this morning. Still not a welder, but I reckon it looks a little better than the first one.

View attachment 171578

24 March 2026

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I'm pretty sure you'll be fine and dandy with those welds!

 

[Paul Allwood]

I'm pretty sure you'll be fine and dandy with those welds!

Thanks - I hope you're right.

 

[Paul Allwood]

Measure twice.....and check both sides....

I thought I had better check the fit of the new rear wheels this afternoon before I get the tyres fitted so I removed the right side rear wheel. On this side the wheel studs are M12 X 1.75. Unfortunately I had measured the wheel studs on the left rear where they are M14 x 1.5 which matches the specs. So I had made the bits to adapt the skid steer rims to suit the M14 studs.

No excuse really as I've had the back wheels off several times and had noticed I needed a different size socket for each side.

This is the left rear - M14 x 1.5



This is the right rear - M12 X 1.75. I removed one and drilled and tapped it to M14 x 1.5. I'll do the same with the other 5 tomorrow.



Strewth !!!

 

[Paul Allwood]

All 6 studs on the right rear are now M14 x 1.5 (same as the left rear). I checked the runout of the mounting flange - it's out by about 4-5 mm. I'm not going to bother trying to fix it, so it looks like my F1 dreams are over.

 

[Paul Allwood]

Tyres fitted to rims this afternoon - I reckon they look good.

I'll have a go at getting them on the tractor tomorrow afternoon.