Mazda Miata tire trailer for track days and autocross
If you are into track days or autocross eventually you’ll probably want to move away from regular street tires, and start using the faster 200TW or better rubber. One of the downsides of these fast tires is that they tend to not last so long if you are constantly driving them on the street.
Drivers of larger cars can stash an extra set of tires in the trunk or back seats, but that’s not possible with something small like a Mazda Miata. In this post I show you one solution to this problem, a tire trailer.
What’s the problem with driving track tires on the street?
Most of the tires you see people run at track days are completely street legal. So what’s the deal with not wanting to drive them on the street? For me there are two big reasons why I try not to use track tires on the street whenever possible.
First off, the fast track day tires tend to not last long on track. Usually track tire life is measured in hours of time and heat cycles. Using them on the street can shorten their usable lifespan even further. Do you really want to be wasting tread depth and heat cycles on the street? What if you pick up a nail and damage the tire? Fast tires aren’t cheap.
Wearing out tires isn’t the only reason to not drive your track tires on the street. When used in not ideal conditions some track tires can have really low performance. A lot of track tires have very little grip in the cold and/or wet and can be very dangerous to drive on the street.
I remember one time I was driving to an event in some Hankook RS4’s that were basically heat cycled out (but still had great tread) when all of a sudden there was a downpour. I had to slow down, and even then it took a lot of effort to keep the car under control going straight down the road. The following year I picked up a nail on one of these tires and had a blowout on the street.
What is a tire trailer?
The purpose of this post is to help you better understand a solution to needing to bring a second set of tires to a track day, a tire trailer.
Tire trailers are very small utility trailers that you can use to haul a set of tires, and anything else you want to bring to a track day. They have a lot of advantages.
- Small and lightweight, so they can be towed with pretty much anything, and are easy to store when not in use.
- Cheap to buy, cheap to register, cheap to own.
- If you have a small car (like a Miata) it can allow you to bring way more things to the track.
Of course there are some drawbacks.
- A hitch and trailer light wiring need to be added to your car.
- Need to be careful with loading in order to avoid sway or overloading your tongue.
- Backing up these small trailers is a pain (especially with a grabby clutch and no power steering).
Building my tire trailer
Trailer frame
I started with a Northern Tool 40″x48″ trailer frame, it’s basically the same as the Harbor Freight one, but in black instead of red. They come in a box and you have to assemble the frame yourself.
There are other options out there. Harbor Freight sells a folding 4’x8′ trailer which is quite a bit bigger, but not much heavier, and not much more expensive. If I was doing this again I’d really consider going this route since the larger size makes loading it safely easier and more flexible.
I’ve also seen some tire trailers that have been made from trailers that can be pulled behind motorcycles. These tend to have a nicer build, but aren’t as flexible as these bare trailer frames.
If you have a large budget and want something that’s more ready to go then Leroy Engineering sells expensive custom premade tire trailers. These have nicer bearings, suspension, and wheels than the cheap trailers, but you pay for it.
My tire trailer requirements
When I built my trailer I had some goals in mind.
- Be able to hold four 15×9″ wheels securely.
- Be able to hold any tools, spare parts, and other things I need to bring to the track.
- Jack and jack stands
- Torque wrench
- Impact gun
- A set of hand tools
- Be able to hold enough fuel for a track day.
- Fuel at the track can be expensive, and I run E85 which isn’t available everywhere.
Original setup
For my original setup I started with a deck made of 3/4″ Sande Plywood painted black. I chose to go with a deck that overhangs the frame a little bit for extra space, my deck measures 62.25″ x 40″. To mount the deck I used carriage bolts, lock washers, and nuts. I recessed the bolts so that they sit flush with the deck.
Toolbox
In the middle of my trailer, right above the axle, I mounted a Dewalt DWST38000 toolbox. This box is the perfect size for what I needed. It has aluminum rails so I can strap things to the top, and can be locked if needed. It’s bolted through the deck with six bolts, I used some aluminum plates to help distribute the load on the box a little more evenly.
I can store quite a bit in this weathertight box, here is some of what I store in this box.
- 1.5 ton aluminum “racing” jack
- Torque wrench
- M12 tire inflator
- Tire pressure gauge
- Drill
- Gloves
- Battery operated fuel pump for 5 gallon jugs, along with a hand crank pump
- Safety gear (helmet, HANS, gloves, driving suit, gloves, shoes)
- Car cleaning sprays
- Spare brake pads
- Extra oil
I use the rails on the top of the box to strap some larger items. Typically a folding canopy, folding chairs, and a folding table.
Tire storage
I chose to mount the wheels to the front of my tire trailer for optimal weight distribution. In order to secure the tires as well as possible they are secured three ways.
- Each tire sits on a pair of plastic tire chocks I bought from Walmart that are bolted to the frame. These prevent them from rolling when unstrapped.
- One ratchet strap is used per tire, going with the tread of the tire. I have hooks in front of and behind each tire to secure the ratchet straps. This prevents the tires from moving.
- I use a longer ratchet strap going horizontally across the top of all four tires to prevent any side to side movement. This strap is hooked onto the frame.
Fuel storage
On the back of the trailer I have the ability to store two five gallon VP Racing fuel jugs. I used a VP Racing mount bolted to the deck, along with hooks and a ratchet strap to secure them to the trailer.
Packout toolbox mounting
I wanted a little bit more storage and had a little bit of extra space on the back side of my trailer. I chose to use a Packout wall mount, along with hooks and a ratchet strap to allow me to bring some Packout tool boxes with me.
There is a lot of variety in what you can mount to the Packout system. I generally have two small boxes that hold hand tools, and another that holds small things (brake fluid, spare sensors, spare fuses, zip ties, brake pad spreader). Typically I will also use their large cooler to bring food with me, at least when I go to multi day events.
Making some upgrades
I used my original setup for about a year, but eventually wanted to make a few changes.
Lower deck
First I added a lower deck. To do this I used two 2×10 boards cut down to sit just below the trailer axle, and then mounted a 1/2″ plywood deck below that. It’s all secured using really long screws.
I used more 1/2″ plywood to build a front and back panel. These are secured to the 2×10 boards using furniture wood threaded inserts, bolts, washers, and lock nuts.
To prevent the lower deck from sagging I screwed some 1″ x 1/8″ steel bars across the width of the board for some additional support.
I typically store a trailer spare tire, canopy weights, jack stands, and other miscellaneous things in the lower deck.
Below the lower deck I attach a spare splitter for my car in case I damage the splitter on the car.
More fuel storage
The two five gallon fuel jugs worked pretty well, but I wanted a little bit more fuel in case the track doesn’t have E85 nearby for the drive home.
I found a 15 gallon Flo-Fast fuel container that fit within the footprint of my existing jugs. To secure it to my trailer I used some 1/2″ plywood screwed together and bolted to the trailer deck with some L brackets. For additional security I use a ratchet strap to tie it down.
To get fuel out of this big container I bought a hand crank pump and use that to pump the fuel into smaller 3 or 5 gallon jugs that I can then pour into the car.
Radial tires
I got about 3,000 miles out of the set of tires that came with the trailer before the tread was pretty much gone and one of the tires started leaking air.
The bias ply tires worked well, but I wanted something that would last a little big longer and hold up a little better to higher speeds.
I ended up getting a set of 145R12 tires for the trailer. They’re a little bit taller and a little bit wider than the stock tires, but fit perfectly under the stock fenders. Overall I’ve been very happy with these and they result in lower tire temperatures and lower bearing temperatures.
Conclusion
I’ve been very happy with my tire trailer ever since I built it a little over two years ago.
I can hook up my Miata, drive to a track hundreds of miles away with all the gear I need for a weekend, and then drive it all home.
Recently I got a truck and a trailer so we’ll see what’s in store for this tire trailer. I might continue to use it, or maybe not, I might even end up selling it. Towing the Miata is nice, but it costs a lot more and it isn’t exactly quicker to load up after a track day since I need to remove my splitter and bumper to get onto the trailer.