Every once in a while a tire comes along that changes how a whole class races. For flat kart racing, the Hoosier A40T is that tire. If you've been fighting a kart that won't hook up, or you're tired of guessing what to run, this is the one to put on your list. Here's why we think it's a game changer, which size to run, and how to get a set to work for you.
What the A40T actually is
The A40T is part of Hoosier's A Series treaded kart tires. It runs a typical durometer of about 45, the same duro as a D30, which puts it in a soft, grippy range that a lot of dirt racers already know and trust. The step up on the A Series is the way the tire is built to work for outlaw and flat kart racing, and that's where it earns its reputation. If you want the side-by-side with the harder compound, we broke it down in our A40T vs A50T comparison.
Why it's a game changer for flat kart racing
Flat karts live and die by traction. There's no wing pushing you down, so the tire has to do the work. The A40T gives you a soft, forgiving compound that hooks up and lets you drive the kart instead of slide it. In our shop, it's the tire racers ask about by name.
- Grip you can feel. A softer 45 duro bites into the track and gives you something to push against in the corner.
- A tire built for the class. It's made for outlaw and flat kart racing, so you aren't adapting something that was designed for another job.
- Sizes that cover the bases. Three sizes let you match the tire to your kart and your track.
- Easy on the wallet. Prices run from about $75 to $95 a tire, which makes it practical to keep fresh rubber on the kart.
Every racer's track is different, so treat that as a starting point and make your own notes. But if you want a tire that gets your kart working without a lot of fuss, this is where we'd start.
The sizes and their rollouts
Rollout is how far the tire travels in one revolution, and it matters for gearing and for setting stagger. Here are the A40T sizes we stock:
- 10.5x5.0-6: 33.25 inch rollout.
- 11.0x6.0-6: 32.5 inch rollout.
- 11.0x9.0-6: 34 inch rollout.
If you're new to the math, our Hoosier tire size and rollout guide walks through it step by step. Anytime you change tire size, double check your gearing too. The gearing guide will get you back in the right range.
Picking the right size
The numbers in a kart tire size tell you the basics. An 11.0x6.0-6 is a tire about 11 inches tall and 6 inches wide that mounts on a 6 inch wheel. What the size does not tell you is the rollout, and that is where people trip up. The 10.5x5.0-6 rolls out 33.25 inches, while the 11.0x6.0-6 rolls out 32.5 inches, so the smaller-looking tire is not the smaller rollout. Go by the listed rollout, not the name, and put a tape on your own tires if the number matters for your gearing or stagger.
The 11.0x9.0-6 is the widest of the three and has the biggest rollout at 34 inches. Pricing steps up with the size: $75 for the 10.5x5.0-6, $85 for the 11.0x6.0-6 and $95 for the 11.0x9.0-6. Not sure where to start? Call the shop, tell us your track and your kart, and we will point you at a size.
A40T and D30: same duro, so use your notes
Because the A40T runs about a 45 durometer, the same as a D30, any notes you already have on pressure and prep from D30s are a reasonable place to start. Treat them as a starting point, not a final answer. Run the new tire, write down what the kart does, and adjust one thing at a time. If you want to see how it stacks up against the harder compound, read the A40T vs A50T comparison.
Getting the most out of a set
Prep matters
A good tire still needs good prep. Our dirt kart tire prep guide covers conditioners and how to read the track, and you can shop everything in Tire Prep and Tire Conditioners.
Mount them right
Match the tire to a wheel that's the right width, use proper bead lube, and mount it slowly. If you're sorting out wheels, our Van-K wheel guide explains sizes and backspacing, and the beadlock guide covers when beadlocks are worth it.
Check pressure and write it down
One psi is a real change on a kart tire. Use a good gauge, check pressure cold, and keep a notebook. A number you didn't write down is a number you can't repeat. Browse tire gauges and durometers for the basics.
Always check your rules
Tire rules vary by track, series and class. Confirm what your class allows before you spend money. If you're not sure, call the shop and we'll help you sort it out.
A simple routine for a new set
- Mount the tires on clean wheels with proper bead lube and take your time.
- Measure the rollout of each tire and write it down, so you know what you are really running.
- Check pressure cold and record it.
- After each session, note the track conditions, your pressures and how the kart felt.
- Change one thing at a time so you know what worked.
Do that for a few nights and you will have a baseline for your track, which saves you practice time every week after.
Thinking about moving up from a flat kart?
A lot of racers start on a flat kart and move into outlaw. If that's you, our flat kart to outlaw conversion guide lays out what's included and what you still need. Or browse the Flat Karts collection to see what we have.
Frequently Asked Questions
What is the Hoosier A40T?
The A40T is part of Hoosier's A Series treaded kart tires, built for outlaw and flat kart racing. It runs a typical durometer of about 45, the same duro as a D30. It comes in three sizes at Toigo Racing.
What sizes and rollouts does the Hoosier A40T come in?
The A40T comes in 10.5x5.0-6 with a 33.25 inch rollout, 11.0x6.0-6 with a 32.5 inch rollout, and 11.0x9.0-6 with a 34 inch rollout. Always go by the listed rollout rather than the size name when you are setting gearing or stagger.
How much does a Hoosier A40T cost?
Prices run from $75 to $95 a tire. The 10.5x5.0-6 is $75, the 11.0x6.0-6 is $85 and the 11.0x9.0-6 is $95.
What durometer is the Hoosier A40T?
The A40T has a typical durometer of about 45, the same duro as a D30. That puts it in a soft, grippy range that a lot of dirt racers already know.
What is the difference between the A40T and the A50T?
The A50T is the harder compound, while the A40T is the softer 45 duro tire. Our A40T vs A50T comparison breaks the two down side by side so you can pick for your track.
Grab a set of A40Ts
Ready to see what the A40T does for your kart? Shop the full Hoosier tire collection or jump straight to a size: 10.5x5.0-6, 11.0x6.0-6 or 11.0x9.0-6. Not sure which size fits your kart and your track? Call the shop and talk to a racer who's been there.