Want to change tire size on 71 Ford 4100 tractor

Ckerch · 2025-09-18T12:57:28-0400

Currently I have 12.4-38 rear tires on my 71 Ford tractor and would like get recommendations on tire sizes.

I use the tractor on my 10 acres to do yard work, brush hog field, removing brush/little trees ...etc. Would like to go wider and possibly turf tires. I know I will need to change rims which is OK. Also, wouldn't mind if I went to lower profile tires to give me couple inches drop and allow me to get it in a garage.

Appreciate any feedback
Carl

TractorTech · 2025-09-18T15:26:04-0400

Welcome to TBN!

The best all around turf tire for the rear of that size tractor is a 16.9x24, R3. It is a popular size that gives good flotation and traction. Most of the old Ford skiploaders (tractor loader industrial) used 16.9x24, R4, so if you have a used tractor yard nearby, you could use those wheels.
I believe 16.9x24s ara a little smaller too.

Ckerch · 2025-09-18T18:14:00-0400

TractorTech said:
Welcome to TBN!

The best all around turf tire for the rear of that size tractor is a 16.9x24, R3. It is a popular size that gives good flotation and traction. Most of the old Ford skiploaders (tractor loader industrial) used 16.9x24, R4, so if you have a used tractor yard nearby, you could use those wheels.
I believe 16.9x24s ara a little smaller too.

This is the direction I wanting to go. With the smaller rear tires, would I need to replace the front tires too?

Thank You
Carl

azbinder · 2025-09-18T18:37:59-0400

Sounds like you have a "row crop" style tractor. Utility style tractors have 26"/28" rear tires. You would also have to change front axle outer extensions and spindles. Would help if you could get us the model number off of the ID plate under the hood. A side picture of your tractor would be good also.

Ckerch · 2025-09-18T20:10:51-0400

i will get you a tractor picture tomorrow since is dark here now. I believe this was initially owned by the road commission because it does have orange paint under the blue.
Attached is the tag inside the hood

Thanks
Carl

TractorTech · 2025-09-19T00:10:08-0400

Interesting tire choice for a road department tractor. What size are your fronts now? The 16.9x24 is 51" diameter/25" radius, while the 12.4x38s are 60" diameter/30" radius approximately so you are dropping 5" lower. There are smaller tire/wheel combinations that might get you what you want.
Another possibility may be 16.9x30 or 18.4x26 R3 which would be very close in size to what you have now.