12-volt electric tyre pumps
Electric pumps available vary greatly: Some are quick, efficient and costly and others are simple devices more efficient at converting noise into heat than inflating a tire.
When selecting a pump, the volume of air pumped is the issue, not the pressure. Look for a high cfm (cubic feet per minute) or lpm (liters per minute). Most imported pumps indicate cfm. Anything under 1 cfm is going to be slow. Anything over 1,3 is going to be reasonable. Not many perform better than 2 cfm. The pressure rating is not important as long as the pump can reach 4-bar. Note: The volume of air must be measured under pressure. Some pump’s specifications look outstanding until they are applied to a half-pumped tire and then they fall off dramatically.
Electric pumps are fairly reliable, but if they break down they are not easy to repair. It’s therefore advisable to carry a foot pump as a backup. Foot pumps are perhaps a little less strenuous to use than hand pumps, but their use in sand can be awkward. They should be placed on a plate or tarpaulin to keep sand from entering the mechanism.
Solutions to the dilemma of letting tyres down quickly have plagued mankind for oh, at least 25 years. Tools range from the long fingernail, a twig or matchstick, the tip of a Leatherman or penknife and recently auto deflators like the Staun, which is the best of them. Screw them onto the valve of each tire and they deflate each to a preset pressure. But I have found something I like even more: The ARB EZ-deflator. It is very fast, very convenient and safe: there is no guesswork that each tire is at the desired pressure (pictured left).
The most accurate and reliable pressure gauges are not digital. The best ones are the more expensive analogue gauges that have a clear gauge measuring in a wide arc, pressures up to but not exceeding 4-bar. The reason for this is that gauges designed for trucks will measure accurately at high pressures, but inaccurately at low pressures. Off-roaders need accuracy between 0.2 bar and 3 bar.
Repairing a puncture
Tyre maintenance tool kit:
• Electric tire pump
• Foot tire pump
• Tubeless repair kit/Tube repair kit combination
• 2x tire levers
• 2nd spare wheel
• Spare inner-tubes
• Jacks and tools to remove and replace wheels
• Spare valves and valve tool
• Pressure gauge
Carry a second spare wheel and tube
By carrying a second spare, a puncture need not be repaired immediately. If the second spare is required, this is the time to make a repair. Do not wait until your vehicle is immobile before you make a repair or you may find your vehicle immobilized in a position which makes it difficult for you to work. Change to the spare, drive to a shady place or set up camp and then repair the puncture in a relaxed, unhurried fashion. It may even prove enjoyable and will feel like part of the bushwhacking experience.
Repairing a puncture – tubeless
These instructions are for repairing punctures while the tyre remains on the rim. As these plug repair systems differ slightly, read the instructions that came with your kit.
Locate the item causing the puncture and draw a circle around it. Do not assume that if you find what seems to be a nail/thorn in your Tyre that this is the only cause of the puncture. Look carefully at the entire tyre including the inner and outer sidewalls marking all irregularities. Remove the nail/thorn. Insert the plug into the spiker and apply cement (some systems do not require cement) to the plug. Insert the reamer into the hole and move it in and out a few times to roughen the edges so the adhesive will stick. Insert the plug and withdraw the spiker according to kit instructions. Inflate the tire and splash water over the repair and over any other suspect areas checking for bubbles.
Repairing a puncture – tubed
These instructions are for punctures that cannot be repaired with the tyre on the rim, making allowances for the fact that the tire patch (tube patches do not work on tires) will be cemented (solution for tubes may not work on tires and tire patches) onto the inside of the tire. Read the literature that comes with the repair kit and follow the tire removal procedure below.
Inspect the tyre and mark any objects which could have caused the puncture. Do not remove the object at this stage. Place the flat under your vehicle and use the jack and the vehicle’s weight to break the seal between the tire flange and the rim. Breaking the flange (separating the tire from the rim) is the first and often most frustrating task when repairing a puncture in the bush. The problem is that when the tire is driven over, or crushed using a high-lift jack, the opposite side kicks up. To prevent this, two high-lift jacks placed opposite each other and worked together works well. If you only have a single high-lift, use a bottle jack or similar to prevent the wheel from lifting.
Once the seal is broken, place the wheel on a ground sheet (it is important to avoid dust) and remove the valve. With a basin of slightly soapy water at hand, wet the tire levers. Stand on the edge of the tire and insert the levers between the tyre and the rim. Work your way around the tire until the flange is over the rim. NOTE: Not all wheel rims are symmetrical. Start with the outside (the side with the valve). If you have difficulty removing the flange, try the other side of the rim. Then with the wheel standing upright, remove the tube where
you think the puncture has occurred and mark it. Then remove the rest of the tube, replace the valve and inflate it. The puncture should then become easy to find. Immersing the tube and watching for bubbles is another way of locating the puncture, and may also reveal other defects such as a leaking valve. Mark the puncture and deflate the tube completely.
Repair kits come with a scraper which is then used to roughen around the puncture site after the tube has been dried. Clean away any rubber particles and apply the rubber solution. When it is touch-dry, remove the backing and apply the patch. Rub over the patch
with the round end of a screwdriver handle or similar object until
you are sure that a good bond has been made. Clean out the inside of the tire and remove the object that caused the puncture. This is a good time to inspect the outside too, and remove any thorns, stones or nails that may be working their way through the tire. Dust the tube with talc and fit it inside the tire with the valve intact. Soap the tire flange and, with the tire levers, work your way towards the
valve, pushing the tire over the rim. Be careful not to pinch the tube with the tire levers.
The final stage is to inflate the tire. Roll the wheel looking at both sides checking that the tire is seated uniformly on the rim. Then deflate the tire and re-inflate it. If the tube is not correctly aligned it may split when it is run.
Getting a puncture on a steep slope
I have on two occasions needed to replace a wheel while my vehicle was pointing skyward at about 20°. This is no easy task. Preventing the vehicle from rolling off the jack is the first priority.
These are the steps:
• Wedge all wheels with rocks or chocks.
• Anchor the vehicle using its winch cable or a chain to another vehicle. Do not use stretchable rope or a kinetic strap.
• The winch cable must be fully stretched before jacking can begin.
• Engage low-range first gear and lock all differentials that you can.
• Firmly apply the hand-brake.
• Remove the spare wheel from the vehicle before jacking.
• Have all occupants leave the vehicle before jacking and have them stand to the side. Keep bystanders from walking behind the vehicle.
• Make sure the vehicle remains stable as jacking begins and
• Only remove the rim once you are confident that the vehicle cannot roll further and fall off the jack.
Advice when fitting tyres
I rotate tires every 15 000 kms to even out wear. Balancing should be done every 35 000 kilometers or thereabouts. With heavy 4x4s, only when balancing is radically out is the vibration serious enough to be transferred to the driver. I always oversee the operation when tyre fitters replace or rotate my tires. I make sure this is done properly: All the tires, including the spare, are fitted with metal valve caps to keep out mud and dust. I make sure the wheel nuts are not over-tightened. This is very common. If you are concerned, do the final tightening yourself. The average 4×4 wheel nut should be torqued to approximately: 66 – 74 ft/lbs equivalent to 90 – 100 Nm. The good fitment centers set theirs to 120 Nm, which I think, is too high.