Spring brings longer days, warmer weekends and, for a lot of Geelong families, the first trip of the season with the caravan, camper trailer or boat in tow. Before you head down the Great Ocean Road or up to the Grampians, it's worth spending twenty minutes on the tyres, both on your car and on whatever you're towing. Towing changes how much load your tyres carry and how they behave, and trailer tyres in particular tend to be forgotten until something goes wrong.
Why towing is harder on tyres
When you hitch up a trailer, the tow ball pushes down on the back of your car. That shifts weight onto the rear tyres, which now carry the rear of the car plus a share of the trailer's weight. At the same time, the trailer's own tyres are carrying everything you've packed (water tanks, gas bottles, the annexe, the esky), often for the first time in months. More load means more heat, and heat is what damages tyres.
Start with your car's tyres
Pressure: use the towing figure
Most cars list two sets of tyre pressures on the placard inside the driver's door jamb or fuel flap: one for normal driving and a higher one for full load or towing. The towing figure usually applies to the rear tyres, and it's there because a heavily loaded tyre needs more air to hold its shape. Check pressures when the tyres are cold, before you've driven more than a few kilometres, and set them to the loaded figure for the whole trip.
Tread and condition
Run your hand across the tread and look for uneven wear, cuts or bulges on the sidewall. A tyre that's marginal for everyday driving becomes a real problem under towing loads. There's more weight pressing down, longer stopping distances, and less margin if the trailer starts to sway.
Load rating
If you tow regularly, check the load index on your rear tyres against what your vehicle's placard calls for. Some owners of dual-cab utes and large SUVs end up with replacement tyres carrying a lower load rating than the originals without realising it, which becomes a concern once a heavy van is on the back.
Now the trailer or caravan
Age matters more than tread
Caravan and trailer tyres rarely wear out. They sit in the driveway for months, exposed to sun and weather, and the rubber slowly deteriorates from the inside out. Check the four-digit date code on the sidewall (for example, 2319 means the 23rd week of 2019). Many manufacturers and caravan clubs suggest replacing trailer tyres somewhere around the five to seven year mark regardless of tread, and any tyre showing sidewall cracking should be replaced before the trip, not after.
Pressure: don't guess
Trailer tyres often need much higher pressures than car tyres, and the correct figure depends on the axle load and the tyre's rating. Look for a placard on the drawbar or inside a hatch, or check the caravan's handbook. If you can't find a figure, ask a tyre shop rather than defaulting to what's in your car. Under-inflated trailer tyres flex and overheat, and that is one of the most common causes of blowouts on highway trips.
The forgotten spare
Check the trailer's spare with the same care. It's usually bolted to the drawbar or under the chassis, where it cops road grime and UV all year. Make sure it holds pressure, and that you actually have the tools and a jack capable of lifting a loaded caravan.
Wheel nuts and bearings
Wheel nuts on trailers can work loose, particularly after a wheel has recently been off. Check them with a wheel brace before you leave, and again after the first 50 kilometres or so of a long trip. While you're down there, spin each trailer wheel and listen for grinding or roughness. Bearing problems are a separate issue from tyres, but they tend to show up on the same neglected trailers.
On the road
- Stop after the first half hour and feel each tyre with the back of your hand. Warm is normal; too hot to touch is a warning sign.
- Keep your speed down. Many trailer tyres aren't rated for high speeds, and a heavy rig takes longer to stop in any case.
- Re-check pressures each morning of the trip, especially if you've added or removed weight.
- If the van starts to sway, ease off the accelerator gently rather than braking hard.
A quick check before the trip is far easier than changing a wheel on the shoulder of the Princes Highway. If you'd like a second set of eyes, Global Tyres Geelong in North Geelong can check pressures, tread and age on both your car and your caravan or trailer, and fit new tyres if any are past their best.