Your spare tyre is ageing right now, in the dark, at whatever pressure it last held. Rubber hardens with age whether a tyre rolls or not, and air seeps out slowly even from a healthy casing. Most drivers in South Africa discover both facts at the same moment: at night, on the shoulder, wheel spanner in hand, next to a spare that is soft, perished, or both.
We treat tyres for a living at our fitment centre in Silverton, Pretoria, and the spare is your tyre people know least about. Some drivers have never seen theirs. So this post is about the fifth tyre: how to work out how old it is, what a space saver spare can and cannot do, why the full-size spare under the bakkie needs the same attention, and what we do about all five.
How do I know how old my spare tyre is?
Find the DOT code on the sidewall. It ends in four digits, and those digits are your tyre’s date of manufacture: the first two are the week, the last two are the year. A spare stamped 3219 was made in week 32 of 2019. You need no tools, just a torch and a rag to wipe the sidewall clean.
How to read the DOT code
Most tyres sold in South Africa carry a DOT code moulded into the sidewall: the letters DOT followed by a run of characters. The block that matters for age is the last four digits. Week first, then year. 3219 is week 32 of 2019, which lands in early August of that year. 0124 would be the first week of 2024.
One catch. On some tyres the full code, date block included, appears on one sidewall only. If you find DOT and some letters but no four-digit block, check the other side of your tyre.
Now point that at your spare. If you bought the car new, the spare is usually the same age as the car. If the car came to you second-hand, the spare can be older than anything else bolted to the vehicle, because previous owners replaced the road tyres and never touched the fifth. The DOT code settles it in under a minute.
How fast can you drive on a space saver spare?
Owner’s-manual guidance for a space saver spare tyre is a maximum of 80 km/h, and short distances only. That means it gets you to a fitment centre or home; it is not a wheel you commute on for a week. Your own manual states the figure for your car, so check it before you need it.
Now put 80 km/h on a Gauteng commute. The N1 and the R21 run at highway speed, and at 80 you are holding the left lane with the trucks while everything else passes you. That works for the stretch to the nearest fitment centre. It is a poor plan for a week of Pretoria to Midrand and back. We wrote more about those routes in our practical guide to Gauteng highways.
A space saver spare tyre is also narrower than the wheel it replaces and usually runs at a much higher pressure, printed on its sidewall. The car steers and brakes differently with one fitted. None of that is a crisis. It is a tyre built for one job: a short, slow trip to somewhere the real repair can happen.
The full-size spare nobody looks at
Bakkies and many SUVs carry a full-size spare instead, and its usual home is a cradle under the load bed, where it has hung since the vehicle left the dealership. Boot-mounted spares do no better, hidden under the carpet with the tool kit on top. A full-size spare has no 80 km/h restriction, which makes it the better spare to carry. It is only better if it holds air.
Two things go wrong in storage. Pressure drops a little every month, quietly, so the spare that was correct at the dealership is soft years later. And the rubber ages: heat and road spray harden the compound over the years, and hardened rubber grips less and cracks sooner. Neither problem announces itself. Both show up in two minutes with a pressure gauge and a torch.
Should my spare tyre be checked and treated too?
Yes to both. Checked, because a flat spare helps nobody at the roadside. Treated, because a puncture does not care which of your five tyres it finds. When we apply the Nano Polymer treatment at our Silverton fitment centre, we treat all five tyres in one morning, and the spare is included in the job.
The treatment is a Nano Polymer coating applied to the inside of the tread, the crown of your tyre. It cures and bonds to the inner wall; it is not a liquid sloshing around inside your tyre. Edwin manufactured liquid tyre sealant for sixteen years before he developed this coating, and the move away from liquid was deliberate. A bonded layer stays where it was applied, and because it is applied evenly, wheel balancing is unaffected. In the tread, it seals as it happens, and in most cases you can keep rolling to somewhere safe.
Here is what the coating does not do, stated plainly. Nothing for sidewalls. Nothing for the bead. Nothing for structural damage from a pothole or an impact, and nothing for damage that existed before we treated your tyre. It does not make a tyre indestructible; it makes tread punctures a smaller problem.
So why the spare? Because four protected tyres and an unprotected fifth is a plan with a hole in it. The spare you fit at the roadside becomes your working tyre on the same road, over the same nails, that claimed the first one. Treating all five tyres in one job closes that gap. It also means the spare gets inflated and checked for age by people who handle tyres all day.
Rev Tyre Tech is Edwin and Micheline Petersen’s family business. Six years of trading, more than 7,800 tyres treated, a 4.9-star Google rating, and a second branch in Gaborone, Botswana. Every treated tyre carries The 1.6 Guarantee: five years, or until the tread wears down to 1.6mm, whichever comes first. The exclusions sit above the coverage on that page, on purpose. Read them before you book.
Check yours this weekend
The whole routine takes about two minutes with the car parked.
- Get to the spare. Winch it down from under the bakkie or lift the boot floor.
- Photograph the DOT code, four-digit date block included.
- Check the pressure against the figure on the spare’s own sidewall or the placard in the door frame.
- Look at the rubber. Cracking, perishing, anything embedded in the tread.
Then WhatsApp the photos to us on +27 76 089 4066, along with a shot of the tread and sidewall on your road tyres. You will get a same-day answer on whether the spare is usable or due for replacement.
One morning sorts all five
Treatment happens at Unit 23 Sildale Park, Silverton, Pretoria, by appointment, and takes one morning. We do not do mobile fitment; the car comes to us. All five tyres are treated, spare included in the job.
WhatsApp +27 76 089 4066 with a photo of your tread and sidewall for a same-day answer, or book your morning.