Tyre safety for caravans, motorhomes & tow vehicles
Tyres are the single most important safety item on your rig. They're the only thing connecting you to the road, and when one fails at highway speed the results can be catastrophic. A blowout on a caravan axle at 100 km/h can rip the guard off, shred wiring, and send you into a sway you can't recover from.
The good news is that most tyre failures are preventable. The three big factors are age, pressure and fitment — and all three are things you can check yourself.
Tyre age — the hidden killer
Caravans and trailers typically do very low kilometres. It's common to see a caravan with 30,000 km on tyres that are eight or ten years old. The tread looks fine — plenty of depth, no flat spots — and they sail through a warrant inspection. But the rubber is quietly perishing from the inside out.
UV exposure, ozone, temperature cycles and simple time all degrade rubber compounds. Sidewalls develop micro-cracks (often invisible until you flex the tyre by hand), internal plies lose adhesion, and the tyre becomes brittle. The result is a blowout — not a slow puncture, but a sudden, violent failure, often on a hot day at highway speed when the tyre is working hardest.
This is the single most common cause of caravan tyre blowouts in New Zealand — old rubber that looks fine on the surface but has lost its structural integrity underneath.
Check your tyres now
Find the DOT code on your tyre sidewall — look for the letters DOT followed by a string of characters. The last four digits tell you the week and year the tyre was made (e.g. 2319 = week 23 of 2019).
Correct tyre pressures — why they matter
It's tempting to drop pressures a little for a softer ride, especially on gravel. But under-inflated tyres are a serious risk when towing or driving a loaded motorhome.
When a tyre is below its correct pressure for the load it's carrying, the sidewalls flex more than they're designed to with every rotation. That extra flexing generates heat — a lot of it. At highway speed, an under-inflated tyre's internal temperature can climb quickly into the danger zone. The heat breaks down the rubber and weakens the bond between the plies. Eventually the tyre gives way. This isn't a slow leak; it's a structural failure at speed.
Over-inflation isn't great either — the contact patch shrinks, grip drops, and the ride becomes harsh — but under-inflation is far more dangerous because of the heat factor. A tyre that's 10–15 psi low on a loaded caravan in summer can fail within a couple of hours of highway driving.
• Always check pressures when the tyres are cold (before driving or after sitting for 3+ hours). Hot readings are misleading.
• Use the pressure on the vehicle placard (door jamb or fuel flap) for your tow vehicle at the loaded weight — not the maximum on the tyre sidewall.
• For caravan tyres, use the pressure recommended by the caravan manufacturer for your loaded weight. If in doubt, a tyre shop can advise based on load and tyre spec.
• Invest in a decent digital gauge — cheap pencil gauges can be 10 psi out.
• Check pressures before every towing trip, not just at WoF time.
Calculate your correct pressure
The "golden rule": your correct pressure depends on the actual load on each tyre, not just a single number off the placard. You'll need a weighbridge visit to get your loaded axle weights — it's usually under $20 and takes five minutes.
Enter your figures below and we'll calculate a suggested pressure using the LoadSafe NZ formula, plus a 5–10% safety margin.
Your axle & tyre details
From a weighbridge — the total weight on this axle when fully loaded.
From the tyre sidewall — the load index converted to kg.
From the tyre sidewall — the maximum cold inflation pressure.
Motorhome tyres — not all tyres are equal
Many motorhome and large campervan owners fit light truck (LT) or commercial vehicle tyres because they're cheaper and easier to find. This is a common mistake that can have serious consequences.
Motorhomes have very different weight distribution and handling characteristics to a standard truck or van. Purpose-designed motorhome tyres (often branded as "camping" or "CP" tyres by manufacturers) are built with stiffer sidewalls, higher load ratings for sustained highway use, and compounds tuned for vehicles that sit for long periods and then do extended highway runs.
A light truck tyre might have a similar size and load index on paper, but it's designed for a different duty cycle — frequent short trips with variable loads, not sitting in a paddock for three months then doing 600 km up the coast with 4 tonnes on board. The construction and compound are different, and those differences matter when the tyre is working hard.
• Check for the CP (Camping Pneu) marking — this is the European standard for motorhome-specific tyres and is the gold standard.
• Make sure the load index matches or exceeds your axle weight when fully loaded (weighbridge figures, not guesses).
• Talk to a tyre specialist, not just a general tyre shop. Not all fitters understand motorhome requirements.
• Budget for proper tyres. The price difference between a generic LT tyre and a quality CP tyre is small compared to the cost of a blowout at open-road speed.
General tyre care for tourers
• Check pressures cold on all tyres including the spare.
• Walk around and visually inspect sidewalls for cracks, bulges or cuts.
• Make sure wheel nuts are tight (re-torque after the first 50–100 km if wheels have been off).
• Check tread depth — legal minimum is 1.5 mm in NZ, but for towing you want significantly more than that.
• If your caravan or motorhome sits for weeks or months between trips, inflate tyres to the maximum sidewall pressure to reduce flat-spotting.
• Move the vehicle occasionally, or use tyre cradles to take the weight off.
• UV degrades rubber — cover tyres or park in shade if possible.
• Don't rely on tyre shine products as UV protection; they can actually accelerate cracking on some compounds.
Please note: This page provides general guidance only — it is not professional or engineering advice. Always follow your vehicle and tyre manufacturer's recommendations. If in doubt, consult a tyre specialist. All care, no responsibility.
How to check caravan and motorhome tyre safety
Tyre failures on caravans and motorhomes don't usually happen because of bad tread — they happen because the tyres are simply too old. Caravans sit for months between trips, often outside in NZ sun, rarely turning. The rubber dries out and cracks long before the tread gets worn down, and the first sign is often a sidewall blow-out at 90 km/h on State Highway 1. Touring Brain's tyre safety check is built around the two things that genuinely matter: how old your tyres are, and whether they're inflated correctly for your loaded weight.
Every tyre has a DOT code on the sidewall — a four-digit number stamped after the letters DOT, indicating the week and year of manufacture. "3621" means week 36 of 2021, so a tyre that's now four-and-a-bit years old. Most caravan industry guidance suggests replacing tyres at five years regardless of tread, and never running anything older than seven. The check on this page reads your DOT code, calculates current age, and tells you whether you're inside the safe window — with a colour-coded warning so there's no ambiguity.
Pressures matter too. A loaded caravan or motorhome needs higher pressure than the same vehicle empty — often 60–80 PSI on a heavy single-axle van versus 40–50 PSI on a light camper. Under-inflation generates heat, and heat is what kills tyres on a long drive. The pressure calculator takes your tyre's load index, the actual axle load, and the manufacturer's recommended pressure table, and gives you a target cold pressure to set before you leave home.
Frequently asked questions about caravan and motorhome tyres
What is a DOT code and where do I find it?
The DOT code is a sequence stamped on the tyre sidewall after the letters "DOT." The last four digits are the manufacture date — the first two are the week, the last two are the year. So "DOT ABCD 1224" means the tyre was made in week 12 of 2024. It's usually only stamped on one side of the tyre, so you may need to look at the inside sidewall.
When should I replace caravan tyres on age?
The widely-accepted industry guidance is to replace caravan and motorhome tyres at five years from manufacture regardless of tread depth, and to never run a touring tyre older than seven years. Caravans rack up few kilometres but sit in the sun for long periods, so they age out long before they wear out. UV, ozone, heat cycles and load cycles all degrade rubber compounds.
What's the difference between load index and speed rating?
The numbers and letters at the end of a tyre size (e.g. "112T") are the load index and speed rating. Load index 112 means the tyre can carry 1,120 kg at maximum pressure; speed rating T means rated up to 190 km/h. For caravans, the load index is the critical number — under-rated tyres are a common WoF/CoF fail and a real safety risk. Speed rating matters less for tow rigs but should still meet or exceed the vehicle's original spec.
When and how should I check pressures?
Always check pressures cold — before the tyres have warmed up from driving. Heat increases pressure by 4–6 PSI, so a hot reading isn't comparable to the manufacturer's cold-pressure recommendation. Check at least monthly during touring season and before any trip over 200 km. A digital gauge is more accurate than the gauges on service-station compressors.
What sidewall damage means I should replace immediately?
Bulges (a swelling on the sidewall) mean the internal carcass has separated — replace immediately, that tyre will fail. Visible cord, deep cracks running around the sidewall circumference, or any cut deeper than 6 mm are also immediate-replacement signs. Surface checking and fine "weather cracking" is age-related and usually means the whole set is due.
Will old tyres fail a Warrant of Fitness?
NZ's WoF/CoF criteria don't have a hard age limit on tyres, but inspectors will fail any tyre with visible cracking, bulges, cord or unsafe sidewall damage — which is what old tyres tend to develop. Don't rely on the WoF to spot tyre age for you; use the DOT code yourself.
More tools for New Zealand touring
- Towing calculator — check tow rating, ball weight and ATM against NZ legal limits.
- Motorhome GVM check — make sure your payload is under gross vehicle mass.
- Pre-departure checklist — nothing forgotten before you hit the road.
- Plan a route — Loop, A→B with stops, or destination-mode trip planning.
- 3-day weather briefing — wind, rain and gust forecasts.
- Find NZ campsites & holiday parks — DOC and OSM data on a map.