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Tyres and wheels are pretty crucial in HO slot car racing - they determine grip and also influence front end stability and magnetic downforce. It’s possible to write a whole book on the subject, but here are the important bits…

1. Round and true

The first thing to say is that wheels and tyres need to be round and sit true on the track. Otherwise the car will hop, break traction and move those all-important traction magnets up and down. The easiest way to ensure round tyres is to replace the stock rubber tyres with specially made racing tyres, like Super Tires.

Although the stock wheels (the ones a car comes with) will usually be fairly round, they can be made rounder by removing the tyres and sanding them under power. Alternatively - if the class rules allow it - replace them with racing wheels, such as the Quicker Engineering rear hubs we have in the club shop.

2. Front wheels

We often replace the front wheels with a special racing front end - we sell Wizzard and Viper sets in the shop. These are nice and round, with less surface area and are lower profile.

Using smaller diameter front wheels and tyres allows the front of the car to sit lower, meaning the guide pin is lower in the slot and de-slotting in corners is reduced. Less surface area means the front wheels are less likely to drag, increasingly front-end stability in corners.

3. Grip

Reducing front grip is good for front-end stability. On the back, we definitely want more grip - for traction under acceleration and increase stability through the corners. On the plastic track we use at the Barn, silicone tyres - like Super Tires - work best. For most of the cars we run, softer compounds (the Super Tires A compound) gives maximum grip. For some WHO Mod cars with really strong magnets, harder tyres (like Super Tires B compound or Wizzard TTT hubs and tyres) work best as they don’t compress - or ‘squish’ - under the force of the magnetic downforce. Running a lower profile tyre (the Life Like Series Super Tires, for example) with a bigger wheel also reduces ‘squish’.

4. Wheel and Tyre Height

Adjusting the overall wheel and tyre height is all about adjusting the power of magnetic downforce. Increasing the height raises the traction magnets away from the steel rails in the track and so reduces magnetic downforce. Decreasing the height lowers the magnets onto the rails and increases downforce.

Increasing downforce means the car is ‘stuck down’ and can corner quicker - just like in real racing. However, the car will be slower on the straights and the motor will be worked harder, causing it to heat up more.

Finding the right wheel and tyre height is finding a balance between straight-line speed and downforce - and keeping an eye on heat build-up in the motor. It will also depend on your driving style.

For example, some racers may prefer a ‘slammed’ car, always running on the lowest height, whereas others might find that set-up undriveable and will go up at least .008” in height or more. Tiny fractions of an inch can make a lot of difference to handling.

In HO slot cars, wheel and tyre sizes are measured in inches. So .442” is four hundred and forty-two thousandths of an inch - or “four-four-two” for short. All Super Tires are marked with their size and the Quicker wheels are different colours to indicate different sizes. There are two very useful charts opposite to click, view and save.

Tyre gauges are also available to measure tyres and wheels - we sell a good-value plastic gauge in the shop. The metal BSRT gauges are available from Lucky Bob’s.

- Andy Player

Tyco & 200 Series Super Tires plus Quicker wheel

size chart (with permission). Click to view

Tyres & Wheels Tech

Formula One Tyco with Quicker rear wheels fitted with Super Tires, plus a Viper front end.

A box full of Quicker Engineering wheels

Life Like Series Super Tires plus Quicker wheel

size chart (with permission). Click to view

Thanks to Super Tires for the use of their wheel and tyre charts above and for sponsoring events at WHO Racing.