The debate between Firestone’s 23-degree radial tire and Michelin’s 45-degree tread bar angle is nearly as old as the red vs. green debate. If you haven’t decided which “side” you’re on, we can help you understand differences between these two tread styles, and in what conditions each will perform best.

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There is no “winner for all.”

Since Firestone first introduced the 23° tread design in 1950, it has promoted the tire as having better traction than competitors’ tires. The company has even “proven” it in a head-to-head tug-o-war against Michelin as seen in the video below. While Firestone’s 23° tread design does perform better than the 45° tread design under certain field conditions, there are conditions in which the 45° tread design will come out ahead.

Understanding the difference in tread designs.

Before we dig into the performance differences between the 23° and 45° tread designs, here is an overview of their key design differences.

As seen in the figure below, Firestone’s flatter and slightly closer-spaced 23° tread bar design puts more bars in contact with the ground, delivering 15% better bar-to-ground contact than 45° tread bars. However, the differences in lug spacing and tread bar angle impacts performance as the soil and field conditions change.

Comparison between Firestone's 23° tread design and the 45° tread design
Firestone's flatter and slightly closer spaced 23° tread design puts more lugs in contact with the ground than the 45° tread design.

Why did Firestone choose 23 degrees for their tread bar angle?

Was it because the earth also rotates at 23 degrees? Probably not. Since the company began creating pneumatic tires in 1932, rigorous testing has been a key component of product development. Firestone tires are tested 24 hours a day, every day of the year at the Firestone Farm Tire Test Center in Columbiana, Ohio. This is where the 23° tread design was developed, tested, and evaluated—a tread design that continues to deliver industry-leading performance nearly 70 years later.

Which tread style is better: 23 or 45 Degree?

When deciding which tread design is best for you, here are some key considerations:

  1. Application/use
  2. Field and soil conditions
  3. Roading performance
  4. Tire life

The 45° tread bar angle is usually the better choice for farming on hillsides.

If you farm the sidehills, the 45° tread design may be a better choice, especially if you need to stay between the rows for in-season passes across the field such as spraying, cultivating, or side-dressing nitrogen. The straighter 23° tread bar lends itself to more side slippage or “dog-tailing” when driving on hillsides, which could mean driving on the crop and/or extra cultivator blight.

The 23° tread bar angle has better traction on firm, dry ground.

Planting season is the one time of year when most equipment will benefit from the 23° tread design. Soil is generally dry to moderately dry, and these conditions give Firestone’s 23° radial tire, with its closer spaced lugs and flatter tread angle, a traction advantage. But if you find yourself in the middle of a wet spot or having to pull through a wet harvest season, you’ll wish you had the better cleanout properties and wider lug spacing of Michelin’s 45° tread. In wet field conditions, Firestone’s 23° tread packs itself full of mud and quickly loses traction.

This also means if you’re working in smeary, wet conditions such as in cattle yards, a 45° tread bar might be a better choice.

Which tire roads better?

If you’re switching from bias tires to radial tires, both Firestone’s 23° radial tire and Michelin’s 45° radial tire will be a substantial improvement. Radial tires inherently provide a smoother ride on the road and wear more evenly than bias tires.

In our experience, both the 23° and 45° tread designs provide a good ride quality on the road. However, Firestone’s 23° tire seems to wear a bit more uneven.

The tread life is shorter on Firestone’s 23° R-1 tire.

A new 480/80R42 Firestone Radial All Traction 23° R-1 tire has a tread depth of 50/32nds. A new Michelin 480/80R42 AgriBib R-1W tire has a tread depth of 69/32nds—over 25% more tread depth than Firestone’s R-1 tire. When considering the long-term traction performance of the tire, the Michelin R-1W tire will provide more life. The fact is especially important to consider when buying a used Firestone 23° tire.

NTS Tire Supply specializes in selling used agricultural tires, and it isn’t all that uncommon to hear a customer complain about a 50 percent tread Firestone tire being “nearly bald.” Every used tractor tire we sell is precisely measured across the entire face of the tire, so it’s not that we labeled the tire incorrectly. Firestone’s 23° R-1 tires just have less tread depth.

To further illustrate this point, consider a 480/80R42 Firestone 23° R-1 tire versus a Michelin 45° R-1W tire as it begins to wear. The Firestone will have 37/32nds tread depth left at 75 percent tread and the Michelin will have nearly 52/32nds tread depth remaining at 75 percent—that’s more than a new Firestone 23° R-1 tire! So the next time you’re looking to buy a used Firestone 23° R-1 radial tractor tire, compare the tread depth measurements, not the percent tread remaining.

Tread depth comparison between the Firestone Radial All Traction 23° R-1 tire, Firestone Radial Deep Tread 23° R-1W tire, and Michelin AgriBib R-1W tire
A 75 percent tread Michelin AgriBib R-1W tire still has more tread depth left than a new Firestone Radial All Traction 23° R-1 tire. This difference in tread depth is especially important to consider when buying a used tractor tire.

The Firestone 23° degree lug also has a tapered design which causes it to increase in width and lose its sharp angle as it wears. The Michelin lug width remains constant helping it maintain its sharp lug angle for better traction over the life of the tire.

Cross section of a Firestone 23° lug compared to a Michelin lug

An important note on tire life. 

We feel it’s important to mention that tread depth is not the sole determining factor as to how long a tire will last. Different tire companies have different rubber compound qualities, different tread bar widths, and other manufacturing variances that will impact the life a tire. There can even be quality differences within a tire company. For example, Firestone’s new Performer Evo tire lineup includes “budget tires” that won’t hold up under the same rigorous conditions as Firestone’s standard radial tires. However, the Michelin and Firestone tires compared in this article have comparable quality levels—we consider both to be premium tires.

Is Firestone’s Radial Deep Tread 23° R-1W tire a better option for wet traction and tire longevity?

Firestone manufactures a 23° R-1W tire called the Radial Deep Tread 23° tire. This tire features a 25% deeper tread than its standard R-1 tire while maintaining the 23° tread bar angle. When new, the Firestone Deep Tread tractor tire measures in at 63/32nds—just 6/32nds shallower than Michelin’s R-1W tire. Firestone markets this tire as having “improved wet traction” performance. However, we are skeptical of this claim because the 23° tread bar angle still won’t clean out as well as Michelin’s 45° tread bar angle in wet soil. As mentioned above, if you’re looking to get better wet traction, we advise choosing the Michelin 45° tire over the 23° Radial Deep Tread.

But if you’re looking at two used Firestone radial tires with 75% tread remaining to tackle moderate to dry soil conditions, the Radial Deep Tread 23° R-1W tire will provide you with a value that is closer to a new Firestone 23° R-1 tire.

Click here to view our current inventory of used Firestone 23° radial tires.

Get unbiased tire advice from the NTS Tire Supply Traction Team.

We provide our customers with new and used farm tire options from every major brand. Why? Because we believe the best purchase decision is different for each person. If you’re still questioning which tires are best for your operation, we can help. Drop us a line or give us a call at 888-787-3559.

If you know what you need, click here to shop our online inventory of new and used farm tires.

Posted 
July 1, 2019
 in 
Knowledge Guide
 category.

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