20.8-38 Tractor Tires

Buying 20.8-38 tractor tires

20.8-38 is a large rear tire for high-horsepower two-wheel-drive and front-wheel-assist tractors. It is 20.8 inches (about 528 mm) wide on a 38-inch rim, about two and a half inches wider than an 18.4-38. It is common on tractors doing heavy tillage, and it is often run in duals.

This is the bias version. The radial equivalents are 20.8R38 and the metric 520/85R38, the same tire under two naming systems. Radials give more traction and less soil compaction for the same load, which counts on a tractor that spends long days pulling. See our 520/85R38 page for the radial specs.

What to check

• Rim width: a 20.8 tire needs a wider rim than an 18.4. Check the marking on your wheel (for example DW18L) before moving up a size.
• Clearance: if you are changing from 18.4-38, check fender and frame clearance, and the spacing between duals.
• Load rating: match the ply rating or load index on your current tires, or go higher.
• Used tires: ask for the tread remaining, sidewall photos and the date code. Look for cracks at the base of the lugs.

Tell us how many you need, new or used, and the delivery location for a quote with shipping.

What else is 20.8-38 called?

You will see 20.8-38, 20.8×38, 20.8/38 or 20.8 38: a bias-ply tire 20.8 in (528 mm) wide for a 38 in (965 mm) rim. The radial version is 20.8R38, sold as the metric 520/85R38. Retail listings show 20.8-38 in R-1 tread from several makers, including heavier 14-ply versions.

How does 20.8-38 compare with the other 38 in rim sizes?

The radial 520/85R38 is about 0.6 in (15 mm) lower than the bias 20.8-38 on paper, so it is the close match. Check the new height against fender clearance, and on a front-wheel-assist tractor use the lead-lag calculator. Larger tractors often run 20.8-38 as duals. Both tires on a side must match, and the tractor needs the right hubs and spacers.

What do 20.8-38 tires cost on our site?

We list 4 models in 20.8-38. 4 have a listed price, from $1,484 (Galaxy Earth-Pro R-1) to $2,083 (BKT TR 135) per tire, with a median of $1,717. Prices are per tire in US dollars and change with stock and season.

How tall is the 20.8-38 tire?

The nominal overall diameter is about 73.4 in (1,863 mm), which gives a rolling circumference near 23 in (5,854 mm). That figure is an estimate that assumes an 85% aspect ratio, the usual rule for old inch sizes. Real tires vary by make and load, so treat it as a guide and use the tire diameter calculator or the lead-lag calculator before you change size on a front-wheel-assist tractor.

Is 20.8-38 a radial or a bias tire?

It is a bias-ply size. The dash in the size marks bias construction, which costs less and has stiffer sidewalls. See the radial vs bias guide.