Why you shouldn’t use your tyre repair kit, according to a mechanic

Got a flat tyre – and only a tyre repair kit? Only use it if you absolutely must, says a veteran roadside assistance mechanic.

If you are stranded in the middle of nowhere with a flat tyre and your vehicle’s only solution is a tyre repair kit, you should use it only as a last resort.

RELATED: The hybrid SUVs available with a spare wheel

At least, that’s the advice of the veteran roadside assistance mechanic we spoke to for this article.

While having a puncture repair kit as your only back-up in the event of a flat tyre is okay for city living, if you often drive long distances in the countryside, or live rural, a full-size spare wheel and tyre remains the gold standard for flat-tyre contingency options.

For the inevitability of driving over a nail or similar, it pays to know what your vehicle has as a back-up plan.

What is a tyre repair kit?

Many car manufacturers now sell their vehicles with a puncture repair kit or a tyre repair kit in place of a spare wheel.

A tyre repair kit comprises a canister of liquid sealant and a small air compressor, the idea being that when you get a flat, you attach the can to the tyre valve and pump in the sealant, which patches up any holes. The compressor then pumps the tyre back up enough to get you straight to a tyre shop for repairs.

Puncture repair kits only work for holes smaller than about 3mm.

Manufacturers fit these kits to vehicles so they can offer a larger fuel tank, a third row of seats, a bigger boot, a hybrid or electric battery, or all of the above. As wheels and tyres themselves have gotten bigger – 18-inch rims used to be the preserve of sports cars only, not family SUVs – squeezing in a full-size spare wheel has gotten harder. 

Some manufacturers fit a narrower “space-saver” spare wheel instead of a puncture repair kit, or fit their vehicles with run-flat tyres, while others offer a full-size spare wheel and tyre – which remains the most desirable contingency option.

A tyre repair kit will look something like this, and is normally found stored under the boot floor (or in the frunk of an electric car like this Volvo XC40 Recharge).

When should I not use a tyre repair kit?

It is not recommended to drive long distances after using a puncture repair kit, or exceed 80km/h. Ask yourself it this applies to your current circumstances.

Most of the time, a tyre repair kit will not damage your car, your wheel or your tyre. But there’s an increased risk that it will.

“Sometimes those kits, when they harden, it ruins the tyres because you can’t balance it,” explains Rob, who’s been a roadside assistance technician for nearly 20 years. 

“It’s got the goo on the inside. Ninety nine percent of tyre shops won’t repair a puncture where you’ve put the goo on the inside. Sometimes it’ll actually stick to the rim and you’ll have to get a new rim as well.”

What should I do instead?

If you have a near-new vehicle within the manufacturer warranty, check to see if you have roadside assistance. If you do, call and ask them to tow you to the nearest tyre shop, where getting a tyre fixed could take as little as 30 minutes. This could save you having to buy a new tyre, or even a new rim, and most roadside assistance providers offer the service for free, including the towing.

“The tyre goo repair kits, we always recommend a tow on those, unless it’s an emergency situation and they have to get somewhere,” explains Rob.

When to use your tyre repair kit

Puncture repair kits are for emergency use only. If you don’t have roadside assistance, or can’t wait for them, and urgently need to get somewhere, use the kit to get you out of trouble.

Whatever the case, get yourself to a tyre repairer as quickly as possible to reduce the risk of any damage to the tyre or wheel.

Don’t forget to check the use-by date

The sealant in tyre repair kits can expire. Make sure you check yours regularly – there should be a ‘use-by’ date printed somewhere – and replace it as-needed.

It goes without saying, if you use your tyre repair kit, make sure you replace it otherwise you could get stuck with a flat tyre the next time around – and we don’t recommend hitchhiking. Better yet, see if a full-size spare can fit in your car.

Have you ever had a tyre repair kit damage a wheel? Or has one saved your bacon, rendering you eternally grateful? Let us know in the comments below.

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