Nobody buys wheel chocks with any enthusiasm. They sit in a toolbox or a tray, they cost very little relative to what they protect, and the day they matter is a day nobody planned for. Nothing else in the setup works without being switched on, checked or serviced.
That is exactly why the choice gets made badly. A pair of wheel chocks in NZ conditions has to deal with wet grass, boat ramp algae, gravel farm tracks and salt air, and the set that came free with something else is rarely rated for any of it.
The good news is that getting it right costs almost nothing beyond five minutes of measuring.
Nobody Thinks About Chocks Until One Fails
A handbrake is a mechanical system with parts that wear. Trailer couplings rely on a jockey wheel and a surface that stays where it was. Both are single points of failure, and both fail without warning.
A chock is the redundancy. It is passive, it has nothing to seize or lose pressure, and it works while everyone has gone inside. Nothing about it depends on maintenance having been done. That is the entire argument for wheel chocks in NZ yards, ramps and paddocks, and it explains why the cheapest item in the setup frequently carries the most risk.
Slopes, Soft Ground and Boat Ramps
Boat ramps concentrate every hazard at once. A slope, a wet surface, algae growth and a vehicle being manoeuvred with people standing around it. Anything that moves on a ramp moves toward water with nothing to stop it.
Caravans and campers create a different problem, and it is the one caravan wheel chocks exist for. A van parked on uneven ground puts uneven load through the jockey wheel and the stabilisers, and any settling of the ground beneath them transfers that load somewhere else. Overnight settling on soft ground is a well-known cause of vans moving while occupants sleep. Freedom camping sites and farm paddocks both qualify.
Farm vehicles combine slope with surface. Paddock gradients, wet ground and mud on tyres reduce grip to a fraction of what a sealed yard offers, and farm work routinely involves someone working beside or beneath a stationary vehicle. The vehicle does not need to travel far to cause serious injury.
Plastic, Rubber and Timber Compared
Each material behaves differently once conditions stop being ideal.
Timber
Timber is cheap, available and the poorest performer over time. It absorbs water, splits along the grain, and gives no warning before it fails. A timber chock left in a tray through a wet winter is doing considerably less than the owner believes, and it looks fine right up until it does not.
Rubber
Rubber grips well and stays affordable. It hardens in cold, which reduces the grip that made it attractive, and it degrades under sustained UV. Rubber also absorbs oils and fuels rather than shedding them.
Polyethylene
Polyethylene handles the New Zealand mix better than either. It does not absorb water, does not corrode, resists fuels and solvents rather than soaking them up, and stays UV-stable through seasons of outdoor storage. Lower weight helps too, which sounds trivial until you consider that a chock too heavy to carry to the trailer is a chock that stays in the tray.
Chock Size Against Tyre and Load
Size for truck wheel chocks and light-duty units alike follows tyre diameter and loaded weight rather than vehicle category:
- Boat Trailers. Smaller tyres and moderate loads, though the surface is the worst of any application. Grip on a wet ramp counts for far more here than raw size, so surface comes before capacity.
- Caravans and Campers. Larger tyres and significant loaded weight, often parked for extended periods on ground that changes with the weather.
- Farm Vehicles. Wide variation from utes through to tractors and implements. Match to the largest tyre in regular use rather than the average.
- Trucks and Mining Vehicles. Large diameter and high gross weight, requiring the upper end of the range and frequently a pair per axle.
Use gross loaded weight rather than unladen weight for the calculation. A boat trailer with the boat on it and a caravan packed for a fortnight both weigh substantially beyond the figure most owners have in mind.
Inside the OZ CHOKS® Range
OZ CHOKS® are moulded as a single piece, which removes the join that fails first on other designs. There is nothing bonded, bolted or laminated to separate.
UV stabilisation runs through the material rather than sitting on the surface, so wheel chocks across NZ conditions hold their structure and colour through years of exposure instead of going brittle.
Maintenance is nil. There is no treatment, no sealing and no inspection routine beyond checking for physical damage, which suits equipment that spends its life outdoors and unattended. Chemical resistance means diesel, hydraulic oil and marine growth do not degrade the material, which suits a chock living in a boat trailer or a farm ute tray.
The range runs from the OZ CHOKS® 035 for light trailers and passenger vehicles through mid-range sizes to the OZ CHOKS® 155 for heavy trucks and plant. Chocks Accessories including mounting brackets keep the chock on the vehicle, which is the single biggest factor in it being used at all. A chock in the shed protects nothing parked on a ramp.
A Buying Checklist for New Zealand Conditions
Work through these before ordering:
- Measure the tyre diameter on the vehicle or trailer, loaded
- Use gross loaded weight, not tare or unladen figures
- Consider the worst surface you will use it on, not the usual one
- Check for coastal exposure, since salt air rules out untreated metal and shortens rubber life
- Decide on a mounting bracket so the chock travels with the vehicle
- Buy a pair rather than a single unit, since most applications need chocking both directions
- Confirm the rating with the supplier in writing rather than inferring it from the model number
- Check the chock sits flat against your tyre profile, since a poor contact face reduces grip regardless of size
Tyre Diameter, Loaded Weight and Surface
The measurements that determine the right chock take about five minutes with a tape measure and a look at a compliance plate. Tyre diameter, loaded weight and the surface you park on cover almost the whole decision.
FSP New Zealand® manufactures wheel chocks in NZ for the conditions here, from boat ramps through to farm tracks and coastal yards. Sizing can be checked against your own vehicle before you order. A wheel chocks supplier who asks about your tyre diameter before quoting is worth the call.
Frequently Asked Questions
How many chocks does a trailer or caravan need?
A pair of wheel chocks for trailers as a minimum for most applications, chocking both directions of travel. Slope, load and surface condition all raise the number, and a risk assessment sets it for work vehicles rather than habit or convenience.
Do plastic chocks perform as well as rubber on a wet ramp?
Polyethylene resists water absorption and does not harden in cold, so grip stays consistent across conditions where rubber changes with temperature and age.
Can a chock be left permanently on the drawbar?
Yes, with a mounting bracket. The material is UV-stabilised and needs no cover or treatment for permanent outdoor mounting, which is the arrangement most likely to see the chock reach the tyre.
What should retire a chock from service?
Cracks, a worn or polished contact face, or a deformed slope. Any of the three reduces grip, and a damaged unit should leave circulation rather than be kept as a spare.
Do the chocks work on gravel or mud?
Grip drops on loose surfaces regardless of chock type. Repositioning onto firmer ground, additional units or a mechanical restraint may be needed.
