MOTORBIKE TYRES: Legal loopholes means riders should be wary about tyres says John Wheeler.
Under ECE Type Approval regulations tyres cannot be imported into Ireland without bearing the appropriate type approval mark and number. Look for the E mark, about the size of an old 2p coin, on the tyre's side wall.
However, there is a loophole in the legislation: while a dealer can't sell a tyre without this mark, a bike without E-marked tyres can be sold.
No matter what type of "powered two-wheeler" you ride, your tyres are vitally important. A small area, ranging in size from an €5 note to an €20 note, depending on your machine's size is all that keeps you in contact with Planet Earth.
That small area of contact works hard. It has to grip a wide variety of road surfaces. It has to transmit all the braking force and, in the case of the more powerful machines, just one wheel can be transmitting anything up to 150 brake horsepower (bhp) at speeds in excess of 150 miles per hour.
Compared to the tyres on a typical family car, motorcycles are extremely high-tech and, typically far more expensive. They also have a much shorter life.
A "superbike" can wear out a tyre in 3,000 miles or less and for most machines 10,000 miles would be considered good going.
The tyre wall contains a host of information, most of which seems gibberish to the average rider. The really important information is the tyre size designation and service description.
For instance, this little lot, 180/55ZR17(73W)V280, means that 180 is the nominal section width in millimetres, the aspect ratio - the tyre section height expressed as a percentage of the section width (55) and the rim diameter (17) in inches. The R means it's a radial tyre - the word "radial" is also printed on the side wall. The 73 refers to the load index, here it means a maximum all-up weight of 365 kilograms. V280 means the tyre is designed for a maximum speed of 280 kph - or 150 mph.
"Tubeless" means it is a tubeless tyre, if that word is not printed then a tube must be fitted.
Note also the arrow which shows "wheel rotation". Motorbike tyres, unlike most car tyres, are designed to work in only one direction. It's not unknown for a tyre to be fitted the wrong way round!
The tyre will be one of three types: radial, cross ply or bias.
Marked on the tyre wall is the maximum pressure to which the tyre can be inflated, generally expressed as pounds per square inch (PSI) - this will be in excess of the pressure recommended by the manufacturer for your machine.
Many owner's handbooks state recommended pressures in "Bar" and not "PSI" and some owners rely on guesswork, which is not a good idea. A difference of as little as 2 PSI can effect a machine's handling.
Correct tyre inflation pressures are often overlooked. Some riders tell me they don't check their tyres - that's done when the bike goes in for a service, they say. Better by far, given their high cost and the hard work they have to do, to check pressures at least every week, even if you are sure they don't need it.
Not all forecourt airline gauges are as accurate as they should be. Best to carry your own gauge; "digital" guages are very accurate.
Check your tyres for wear every week. It can be surprising just how quickly they wear down. The legal minimum tread depth for a motorcycle is 1mm. For some strange reason this is lower than the minimum depth for a car of 1.6mm.
However, many manufacturers specify a minimum tread depth of 2mms. If your machine is anything but a small, low-powered lightweight, you are likely to find that at around the 2mm mark the machine begins to skip on white paint lines and cat's eyes.
To check wear look into the centre groove. You should see small ridges sunk within the tread running across the groove. Once the tyre has worn down to this ridge it's time to replace.
Another way is to get a tyre tread depth gauge from a motor factors. Even handier, if less accurate is to use the edge of a €2 coin - the rim on the edge is about 1mm.
Rear tyres tend to wear faster than front tyres. With a lighter machine you might find one front tyre lasts twice as long as a rear tyre, on heavier and more powerful machines the combination of a part worn front tyre and a new rear tyre does not give the best handling. Many experienced riders change both tyres at the same time.
Again for the heavier, more powerful machines tyres should be properly balanced. An out-of-balance tyre can suddenly become dangerous as high speed.
Motorcycles are at a distinct disadvantage compared with a car when a puncture occurs, there being no spare wheel. While punctures are thankfully rare, Murphy's Law says they occur when least convenient. Tubeless tyres can usually be plugged using a proprietary repair kit. This is only an emergency repair and should not be relied upon. Besides, the small CO2 bottles supplied in these kits are too small to fully inflate a rear tyre. Far better to carry a 12-volt electric pump which can be connected to the bike's battery.
Tubed tyres can only be repaired by the time honoured method of using a patch. This means carrying a set of tyre levers and knowing how to remove the tyre at the roadside, no mean feat on anything but the smallest machine.
PUNCTURE prevention is better than cure. Do a careful check each week. Remove sharp embedded stone chips. Look for nails and cuts.
Several anti-puncture liquids can be used. These are poured into the tyre through the valve, after removing the valve core. Most manufacturers and some tyre experts do not recommend them - but I've used products as OKO and UltraSeal for over 30 years with no ill effects, even on very powerful machines capable of high speeds.
My only puncture happened just after I had a new tyre fitted. I was returning home intending to add the puncture seal when I got back.
In the early 1960s, when tyre technology was nothing like today's, a brand new tubed-type front tyre, fitted only that morning, suddenly deflated on a fast bend. My bike carried on in a straight line into the front of an Austin A 35. The sharp bow of the sidecar neatly sliced off his offside wheel. I shot through the bike's fairing, sailed over the car and ended up behind it.
My six-month-old son who was sat with his mother in the sidecar flew over a stone wall and landed, unharmed on his "Paddi Pad" in a marshy field, my wife suffered a broken finger and cut forehead. Small wonder I am fanatical about my tyres.