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Testing Coker Tire’s Vintage Mud Tire

Coker Tire’s STA Traxion in a 700-15

In a time when new off-road "experts" and "influencers" with 10 years of experience are positive that the only real off-road vehicles are JKs, JLs, JTs, and a passel of different side-by sides, many lifelong off-roaders find themselves more and more drawn to the vehicles associated with the good-old-days of off-road.

Along these lines, the resurgence of vintage and period-correct WWII and post WWII 4x4s has exploded. Folks are fixing up, restoring, and resto-modding old 4x4s at a staggering pace, and we love it. We bet you won't see many, if any, folks wheeling side-by-sides in 75 years or so.

One problem with this retro 4x4 resurgence is that the tires, namely bias-ply mud tires, which these 4x4s were sold with and were often first upgraded with, are now few and far between.

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Enter Coker Tire, a company with their entire foot in the door of tires and wheels for car and truck restorers around the world. They have several off-road-aimed tires, including military NDTs, STA Super Traxion, STA Super Lugs, and Firestone Knobbys. Our 1946 CJ-2a was running some mud terrain radials that were fine, but they were not quite as fine as a set of 700-15 STA Traxion tires from Coker.

After we found these tires, we just had to have them. So far, we've logged maybe 500 miles on the tires, including a one off-road trip where we saw sand, rocks, gravel, wet rocks, and a bit of pavement. We also look forward to spinning these tires in the mud and snow, but right now Arizona, where we and the flattie live, isn't cooperating. There's no snow and not much mud where we live. We will update our impressions of these tires as we put more and more varied miles on them, despite points ignition and a fussy carburetor. For now, know that with the first few real miles on our tires, we are more than happy from the performance from our retro-cool Bias Ply STA Super Traxions.

What is a bias-ply tire

Radial tires are much more common today than they were 50-70 years ago, and they are now the norm, while bias-ply tires used to be. Radials are more popular today because they dissipate heat better and generally ride better than bias-ply tires. The name and function of both relate to their construction. Radials have sheets of fabric—often made of nylon, rayon, polyester—that run radially or perpendicular to the tread surface of the tire and then have steel belts that run parallel to the tires tread around the circumference of the tire.

Bias-ply tires have a similar ply that runs from tire bead to tire bead at a bias to each other and the tread of the tire. You can imagine the bias-ply starting at one bead, wrapping across the face of the tire, and ending at the other bead. Then there will be another set of plies running at an opposing angle (perhaps 90 degrees) to the first and so on. The main difference is that bias-ply tires have the same number of layers just about anywhere in the tire, same in the sidewall, and under the tread. A radial, because of the steel belts, might only have a few layers of material in the sidewall. As a result, radials ride softer, dissipate heat better, yet they have weaker sidewalls and a lower load rating. Bias-ply tires are often preferred by off-roaders for their strength.

Our Coker STA Super Traxions

Our Coker STA Super Traxions are touted as long-lasting and durable tires that offer exceptional traction for pickups, vans, campers on both highways and off-road. STA Tires Super Traxion tires are cool running (for a radial) with deep-vented shoulders and a wide profile for flotation and traction. The center of the tread is tightly packed to lessen road noise and provide a smoother ride, while the outer husky lugs with sharp grabby edges provide great traction. The tread is siped for wet traction, and the outer large lugs are pinned for studs if you want to run these tires on your retro snowplow. Cleaning out the tread is a snap as the tire rotates with help from rounded interior corners of the lugs.

Our Experience with the Coker STA's so far

We'll admit we don't have a ton of miles on these tires yet, but we did spend most of a weekend running them on dirt roads that ranged from graded granite and loose stones to packed clay and jagged rock faces. The tires never slipped or yielded in any unexpected way, and they allowed us to feel confident in turns with both front tires and both rear tires gripping as expected. With the tires aired down to about 11 psi, running at about 5-30 mph, the sidewalls soaked up large rocks and ridges from areas where water washed across the road or trail. Traction on rocks and loose dirt during climbs was as confident as it was on wet rocks and what little mud we encountered.

Dear Coker, We want more old-school tires

Dear Coker tire, we love your truck and mud tires. How about bringing back some more retro-tastic off-road tires from the past? We'd be willing to bet folks would buy Armstrong Mud and Snows, Gates XT Commando, Formula Desert Dogs and so on. Thanks! Readers what are your favorite old school off-road tires? Let us know. Verne_simons@motortrend.com.

Specifications (as tested)

Tire: Coker STA Super Traxion
Size: 700-15LT
Type: Bias-ply Mud terrain
Load range: C 6-ply
Max load (lb): 1720@45 psi
Approved rim width (in): 5.00 - 5.50
Tread depth (in):
Overall width (in): 7.9
Tread width (in): 6.5
Overall diameter (in): 29
Maximum psi: 45
Weight (lb): 30lbs