Tractor Tires

How to choose tractor tires

1. Start with the size on your sidewall

Every tractor tire has its size molded into the sidewall. Standard bias sizes look like 18.4-38: an 18.4-inch section width on a 38-inch rim. Metric radial sizes look like 520/85R38: 520 mm wide, a sidewall 85% as tall as the width, radial construction, on a 38-inch rim. The rim diameter must match your wheel exactly. Width and height decide whether the tire clears the fenders, fits between your rows and keeps the right ratio with the other axle.

2. Match the tread to the work

3. Bias or radial?

Keep the same construction across an axle: never mix a bias tire and a radial tire on the same axle. On front-wheel-assist (MFWD) tractors, the front and rear tires also have to stay in the right size ratio, so check both axles before changing one of them.

4. Front tractor tires

Two-wheel-drive tractors steer on ribbed front tires, such as 11L-15 F-2. Front-wheel-assist tractors drive the front axle too, so they use lugged R-1 or R-1W tires matched to the rears. Our front sizes run from 5.00-15 for smaller row crop tractors up to 9.00R20 radials for heavy utility work.

5. Buying used tractor tires

• Ask for the tread remaining, or a photo of the lugs next to a tape measure.
• Check the sidewalls for deep weather cracks, cuts and bulges.
• Ask about repairs, and whether the tire has been run flat.
• Read the DOT date code: the last four digits are the week and year it was made. Old rubber cracks sooner, even with good tread.
• Buy matched pairs so both sides of the axle wear and pull evenly.

When should you replace tractor tires?

Lug height is the first thing to measure. Koenig Equipment advises replacing when the lugs are down to about half their original height, because soft-ground traction drops off measurably from there, and below a quarter the tire is mostly cosmetic. Surface weather cracks are usually fine. Cracks that show cord, or splits that reach the inner casing, mean replacement, since repairs on a casing like that rarely pay. Cupped or scalloped lugs usually point to a pressure or alignment problem, so fix the cause before you fit new tires or they will wear the same way.

What air pressure should tractor tires run?

Lower in the field, higher on the road. Lower pressure widens the contact patch, which improves traction and cuts compaction. The same low pressure on a long road haul heats the casing and fatigues the sidewall. The same source gives examples such as 16 to 20 psi (1.1 to 1.4 bar) for a compact tractor on R-4 rears in the field, against 22 to 28 psi (1.5 to 1.9 bar) on the road. Treat those as examples only: your tire's maximum cold pressure and your tractor manual set the real limits. Our tractor tire pressure guide covers the method.

What do IF and VF mean on a radial?

They are flexion ratings. Maxam and Hobby Farms both describe IF (increased flexion) as carrying about 20% more load than a standard radial at the same pressure, or the same load at about 20% less pressure. VF (very high flexion) pushes that to about 40%. The benefit is the same either way: a bigger footprint with less pressure on the soil. The full comparison is in our IF vs VF tires guide.

Do you need liquid ballast?

If you run a front-end loader, usually yes, on the rears. Filling the tire with fluid adds weight low down, which improves traction and counters the load on the front. The usual fill is about 75% of the tire's volume, with the rest left as air. Water freezes, and calcium chloride corrodes rims, so many owners use a beet-juice-based fluid instead. Ask a dealer to fill it. To estimate how much weight you need, use our ballast calculator.

What about R-2, I-1 and I-3 treads?

Three codes you will see beyond the table above. R-2 has lugs about twice as deep as R-1 and is built for rice paddies and cane fields. It wears unevenly on hard roads. I-1 is the implement tread for trailers, planters and other towed equipment, with a reinforced casing for loads and low rolling resistance on the road. I-3 is a bar tread similar to R-1 but with shallower lugs, used for flotation on heavy implements such as manure spreaders and grain carts. Our tread types guide goes through all of them.

Which tires fit a lawn tractor or garden tractor?

Lawn tractor tires and garden tractor tires are small. Sizes show diameter, tread width and rim in inches, so 23x8.50-12 is 23 inches tall, 8.5 inches wide, on a 12-inch rim. Some sizes show only width and rim, such as 9.50-8. Tire retailers Tires-Easy and Giga Tires both describe the same three choices of tread. A turf tread, usually a chevron pattern, is the default for mowing because it grips grass without tearing it. A lug or agricultural tread has deep grooves that clear mud and suit dirt, sand or towing, but it is harsh on a lawn. A rib tread rolls easily and lasts, but pulls less, so keep it for flat, firm ground.

Casing strength is the other choice. A 4-ply (load range B) tire resists punctures better than a 2-ply (load range A), which helps on thorny or rough ground. Pressure on riding mowers is usually low, with 10 to 20 psi (0.7 to 1.4 bar) quoted as typical, but your sidewall and manual decide. We list 18x8.50-10, 20x8.00-10, 23x8.50-12, 26x12.00-12 and 27x8.50-15, and the Carlisle Turf Saver is a turf-tread model. Read the full guides to lawn tractor tires and garden tractor tires, or send us your size on WhatsApp if you are not sure which one fits.

Send us your size and we’ll tell you what we can supply new and used. Ask for photos of any used tire before you buy.