Tire Sizing & Fitment
Firestone Tractor Tire Size Chart: Every Size by Model
A Firestone tractor tire size chart lists every size a Firestone model comes in. We list four Firestone models, from 6.00-16 front tires to 20.8-38 bias rears and a 520/85R38 radial. Each table below shows width and rim in inches and millimeters, so you can match a size to your tractor.
Firestone tractor tire sizes read like a phone number with a rim attached. Good news: it is two numbers and a dash. (Bad news: Firestone also puts a degree sign in some model names, so squinting is allowed.)
A Firestone tractor tire size chart lists every size a Firestone model comes in. We list four Firestone models, from 6.00-16 front tires to 20.8-38 bias rears and a 520/85R38 radial. Each table below shows the width and rim in inches and millimeters. Let’s get to the bottom of this, or at least to the rim.
How to read a Firestone tractor tire size
Firestone sizes follow the same codes as every other brand. In a bias size like 18.4-38, the 18.4 is the width in inches (467 mm) and the 38 is the rim diameter in inches (965 mm). The dash means bias-ply. In a radial size like 520/85R38, the 520 is the width in millimeters (20.5 in), the 85 is the aspect ratio and the R means radial. Multiply an inch width by 25.4 and you have millimeters. Our tractor tire size guide explains every number on the sidewall.
Radial sizes also carry a load index and a speed symbol, such as 125D or 155B. The letter is the speed symbol. In the ETRTO/TRA table, D means 65 km/h (40 mph) and B means 50 km/h (31 mph).
A little history, since the name is older than most tractors on the road. According to Wikipedia, Harvey S. Firestone started the company on August 3, 1900 in Akron, Ohio, and Bridgestone bought it in 1988. Bridgestone’s agriculture page shows Firestone ag tires sorted by equipment type.
Firestone Super All Traction II 23 degree sizes: the bias rear tires
The Super All Traction II 23° is an R-1 bias tire, and it has the most sizes of the four. We list 13, from 11.2-24 to 20.8-38.
| Size | Width in (mm) | Rim in (mm) | Ply rating |
|---|---|---|---|
| 11.2-24 | 11.2 (284) | 24 (610) | 8 ply |
| 12.4-24 | 12.4 (315) | 24 (610) | 8 ply |
| 12.4-28 | 12.4 (315) | 28 (711) | 6 ply |
| 13.6-24 | 13.6 (345) | 24 (610) | 8 ply |
| 13.6-28 | 13.6 (345) | 28 (711) | 6 ply |
| 14.9-24 | 14.9 (378) | 24 (610) | D, 8 ply |
| 14.9-28 | 14.9 (378) | 28 (711) | 6 ply |
| 16.9-28 | 16.9 (429) | 28 (711) | 6 ply |
| 16.9-30 | 16.9 (429) | 30 (762) | 6 ply |
| 18.4-30 | 18.4 (467) | 30 (762) | 8 ply |
| 18.4-34 | 18.4 (467) | 34 (864) | 8 ply |
| 18.4-38 | 18.4 (467) | 38 (965) | 8 ply |
| 20.8-38 | 20.8 (528) | 38 (965) | 8 ply |
Ply rating is a strength rating for the casing, not a count of layers you can see. Don’t pick by ply alone. Check the load table for your weight.
Firestone Performer Evo and Radial All Traction sizes: the radials
The Performer Evo is an R-1W radial, which means its lugs run at least 20% deeper than a standard R-1. The Radial All Traction 23° is an R-1 radial. We list five radial sizes between them.
| Size | Model | Width mm (in) | Rim in (mm) | Load and speed |
|---|---|---|---|---|
| 340/85R24 | Performer Evo R-1W | 340 (13.4) | 24 (610) | 125D |
| 380/85R24 | Performer Evo R-1W | 380 (15.0) | 24 (610) | 131D |
| 420/85R28 | Performer Evo R-1W | 420 (16.5) | 28 (711) | 139D |
| 460/85R30 | Performer Evo R-1W | 460 (18.1) | 30 (762) | 145D |
| 520/85R38 | Radial All Traction 23° R-1 | 520 (20.5) | 38 (965) | 155B |
Watch the speed symbol. The D tires are rated to 65 km/h (40 mph). The B on the 520/85R38 is rated to 50 km/h (31 mph). That matters if you haul on the road.
Firestone front tractor tire sizes: the Champion Guide Grip 3-Rib
The Champion Guide Grip 3-Rib is an F-2 bias front tire. We list three sizes. Front tires are narrow and run on a 15 in or 16 in rim.
| Size | Width in (mm) | Rim in (mm) | Ply rating |
|---|---|---|---|
| 6.00-16 | 6.00 (152) | 16 (406) | C, 6 ply |
| 10.00-16 | 10.00 (254) | 16 (406) | D, 8 ply |
| 11L-15 | 11 (279) | 15 (381) | D, 8 ply |
There is no single front size that fits every tractor. The right one depends on the rear tire and the model, so read the size off the tire you are replacing. Our front tractor tires guide covers the lead and lag rules for four-wheel-assist tractors.
Which Firestone bias size matches which radial?
Our opinion: match the overall diameter, not the name on the sidewall. Equivalents are close, not identical. Take the 20.8-38. It is about 528 mm wide (20.8 x 25.4), and its 520/85R38 equivalent is 520 mm. That is 8 mm in width alone, and you can see why we say to tread carefully.
| Bias size | Close radial | Note |
|---|---|---|
| 20.8-38 (528 mm) | 520/85R38 (520 mm) | Both are Firestone sizes in our list |
| 18.4-30 (467 mm) | 460/85R30 (460 mm) | Same rim, about 7 mm narrower |
| 18.4-34 (467 mm) | 460/85R34 (460 mm) | The radial is not in our Firestone list |
Check any swap with our tire size converter and the manual. Or browse the full tractor tire size chart for every brand.
When you don’t need a Firestone tire, or this chart
Honest answer: this is not the whole Firestone range. We list four models. If your size is missing from these tables, that does not mean Firestone never made it. Send us the size and we will see what we can find.
If your current tire is the right size, holds air and has good tread, keep it. A Firestone name on the sidewall does not make a tire any younger. Check pressure with a gauge before you buy anything. These tables show fit, not pressure, so use the maker’s load and inflation table for your size and weight.
More tractor tire guides from us:
- How to Measure Tractor Tire Size: Width, Diameter and Circumference
- R14 Tractor Tires: Hybrid Tread, Sizes and R4 vs R14
- R1 Tractor Tires: What They Are and Where They Work
- Garden Tractor Tires: Sizes, Tread and How to Choose
- Lawn Tractor Tires: Sizes, Tread and How to Choose
- R4 Tractor Tires: What They Are and When to Use Them
- Farm Equipment Tires: Which Type Fits Which Machine
- Rear Tractor Tires: Sizes, Tread and How to Pick a Pair
- Goodyear Tractor Tires: Who Makes Them and What Changed
- Titan Tires: Who Owns Titan, Where It Makes Them and Are They Good
- Front Tractor Tires: Which Tread, Size and Pair to Buy
- Who Makes BKT Tires? Owner, Factories and Where They're Made
- Big Tractor Tires: How Big They Get, What They Fit and Cost
- How Much Does a Tractor Tire Cost? Real Prices by Size
- IF vs VF Tires: What They Mean and When to Choose Them
- Tractor Tire Pressure: How to Set It for Load and Speed
- How to Inspect Used Tractor Tires Before You Buy
- R1 vs R1W Tractor Tires: What Is the Difference?
- Radial vs. Bias-Ply Tractor Tires: Which Should You Choose?
- Tractor Tire Size Guide: How to Read Every Number on the Sidewall
- Tractor Tire Types Explained: R1 vs R2 vs R3 vs R4
Prices sit on each listing and change with stock and season. See our Firestone tires page, or send us your size on WhatsApp. We’ll find the tire. We’ll probably make a rim joke. It’s free, and it doesn’t need balancing.
Questions
What sizes do Firestone tractor tires come in?
We list 21 Firestone sizes across four models. They run from 6.00-16 front tires, through 11.2-24 to 20.8-38 bias rears, to radials from 340/85R24 to 520/85R38. Each size is in the tables above.
What is the biggest Firestone tractor tire you list?
The widest are the 20.8-38 bias tire at about 528 mm (20.8 in) and the 520/85R38 radial at 520 mm (20.5 in). Both fit a 38 in (965 mm) rim.
What does R-1W mean on the Firestone Performer Evo?
R-1W is the R-1 bar lug pattern with lugs at least 20% deeper. The extra depth helps in wet or heavy soil and leaves more rubber to wear through on tractors with many field hours.
What is the radial equivalent of a 20.8-38 tire?
The close equivalent is 520/85R38. It is not identical: 20.8 in is about 528 mm wide and the radial is 520 mm, an 8 mm gap. Check the overall diameter before you swap.
What size are Firestone front tractor tires?
The Champion Guide Grip 3-Rib comes in 6.00-16, 10.00-16 and 11L-15 in our list. Read the size on the front tire you are replacing, because the right front size depends on the rear tire and tractor model.
What does 155B mean on a tractor tire?
The 155 is the load index and the B is the speed symbol. In the ETRTO/TRA table B means 50 km/h (31 mph). Load index numbers are looked up in the maker's load table.
Who owns Firestone?
According to Wikipedia, Bridgestone bought the Firestone Tire and Rubber Company in 1988. Harvey S. Firestone founded it in Akron, Ohio on August 3, 1900.
Where do I find load and pressure for a Firestone tire?
Use the maker's load and inflation table for your size and weight. Run the lowest pressure the table allows for your load. Our size tables show fit, not pressure.
How much do Firestone tractor tires cost?
In our catalog the Super All Traction II 23° in 18.4-38 lists at $1,383 per tire, and the Performer Evo in 420/85R28 at $1,841 per tire, the highest of the 15 listings in that size. Front tires cost far less. Prices change with stock, so check the listing.
Are Firestone tractor tires radial or bias?
Both. The Super All Traction II 23° (R-1) and Champion Guide Grip 3-Rib (F-2) are bias. The Performer Evo (R-1W) and Radial All Traction 23° (R-1) are radial. A dash in the size, as in 18.4-38, means bias; an R, as in 520/85R38, means radial.