BMW CLUB

From the Club Journal, reprinted with The kind permission of Mike Fishwick - Technical Officer

While punctures are now far rarer than they were, say thirty years ago, they remain one of the most common problems to afflict the motoring public. Of course BMW claim that they only occur every 93,000 miles, this being used as justification for the absence of a spare wheel on their M Roadster etc. To give any odds at all on a random event is something, which no self-respecting bookie would ever dream of! My experience has been that punctures can occur at any time - ask anyone living on a new housing development where nails and screws etc abound. All that one can guarantee is that punctures will usually take place at highly inconvenient times.

Of course, in the days before tubeless tyres became a universal fitment, and all motorcyclists were self-reliant, it was easy enough to fit a spare inner tube by the roadside. This made a complete repair, and the damaged tube could be patched at leisure for future use. While many tubeless tyres can be fitted with tubes, (e.g. on Monolever Boxers), most modern machines use rim and tyre sizes which prevent such a repair being made. There is also the problem of safety while carrying out such a repair, for in many places - even lanes with high hedges - a stationary motorcycle and its rider may not be seen, particularly at dusk, until it's too late. Remember that most car drivers drive to the limit of what can currently be seen, and make no allowances for the unexpected.

Temporary repair sealants, such as the various aerosol - packaged products are a quick way to become mobile again, but can only be used after coming to a stop. They are not suitable for prolonged use, and attach themselves tenaciously to the inside of the tyre casing. In most cases their composition is such that tyre specialists will refuse to repair a tyre, which has been internally coated with such a sealant. In the case of ultra-low profile tyres such as the 'Z' rated types found on many modern motorcycles a flat tyre could be a very expensive experience. The fitting of a vulcanised plug is not always possible if the puncture is close to the sidewall, and a limit of one repair per tyre is usually enforced. Even a gentle stop from speed can cause severe damage to the sidewalls, not to mention the wheel rims. Even without a puncture it is possible to experience rapid deflation, such almost happened to John Coleman during our return from the FIM Rally at Barcelona, when he ran over a rock while climbing towards the Col de I'lseran in the French Alps. The front rim of his R80 deformed to such an extent that the edge of the tyre bead was visible over a length of about two inches. A fraction of an inch more and his front tyre would have deflated immediately, providing a rapid one-way trip to Bonneval - sur - Arc, about a thousand feet below!

The answer to all these problems would obviously be that of a puncture resistant tyre, but in the absence of such wonders a good alternative is to coat the inside of the tyre with a tyre sealant which will always remain sufficiently fluid to fill the puncture as soon as it occurs. It goes without saying that it should not disturb wheel balance, and be capable of being easily removed if necessary. Several such products have been marketed over the years, mainly directed at the motorcycle market. While tyre manufacturers do not recommend their use, no research has ever found sealants to have a detrimental effect. In every case of major damage to the front tyre, for example, the rider has maintained control and stopped safely. While most of them worked well, all had disadvantages. The usual problem was that after prolonged use at high speed the centrifugal force caused the sealant to separate and so lose its ability to seal for long periods. This was coupled with the extreme difficulty in removing the sealant in order to affect a permanent repair, so that a new tyre was the only effective remedy.

Against this background PunctureSafe appears to be the complete answer. It certainly seals well - I have personally attacked a motorcycle tyre with a spike until my arm grew tired, at the end of which pressure loss was negligible. After two weeks of such treatment by the public during a motorcycle show, the tyre had more puncture marks than tread, but still maintained it's pressure. PunctureSafe is claimed to be capable of repairing punctures made by objects up to 6 mm in diameter for the life of the tyre, and in the event of a larger area of damage it will provide protection from rapid deflation. It is water soluble in it's uncured state, and I have seen it being easily washed out of a tyre casing to enable the fitting of a vulcanised plug. Other properties include the ability to virtually eliminate pressure loss, even during long-term storage, and also to extend tyre life due to improved heat transfer from the tread area to the wheel rim. Many motorcycle riders find this increase to be in the order of 50%. This is probably why tyre manufacturers do not recommend its use! All things considered PunctureSafe appears to be the answer to a motorcyclist's prayers, and a telephone call to the UK manufacturers in Exeter, (01395 233951), will find your closest distributor or stockist. Many motorcycle dealers stock PunctureSafe in D.l.Y. graduated dispenser bottles for home use. A measured volume of PunctureSafe - appropriate to the size of the tyre - is injected through the valve body, the small pressure loss being corrected afterwards. The initial quarter mile or so results in a mild imbalance effect which gradually reduces as centrifugal force spreads the sealant over the inside of the tyres in a uniform coating.

Although formulated for use in tubeless tyres, Puncturesafe can also be used with inner tubes, as Cynthia Milton and John Adams demonstrated during their recent trip to Pakistan. John's RI00GS rear tyre was badly damaged by a two-inch long bolt, but retained pressure well enough to be fitted with a new inner tube later. Cynthia was unaware of any problems, but when replacing her R80GS rear tyre after returning home she found the marks of 12 punctures which had been sealed without her even being aware of them! To cover 20,000 miles on one set of tyres through some of the worst roads in the Middle East and Asia without having to even remove the wheels is sufficient testimony for PunctureSafe. I have used it in my car tyres for almost 20,000 miles, and can also confirm its claims.

When one adds the cost of a simple puncture it can be a major problem. Assuming that one manages to stop without injury or damage, there is the nightmare of recovery, (often with additional delay because a motorcycle is involved), at horrendous cost if you are not a member of a suitable organisation. The recovery operation may itself cause damage to your motorcycle if it is badly secured to the 'spectacle' type frame designed to support the front wheels of a car, and may only take you to the nearest garage or service area. It may then be found that the sidewalls and perhaps also the rims are damaged. Then there is the problem of finding a tyre specialist who will repair or change your tyre, not to mention the delay in obtaining a motorcycle tyre of the required size and type, particularly at the weekend. (On weekends in rural France one is simply resigned to waiting until Monday!) It may even be necessary to stay in a hotel for the night. Then comes the cost of the tyre itself, labour charges for changing it, and also to remove and replace the wheel, (Honda Goldwing owners weep at the thought of this!) There are also the general hassles of being a motorcyclist in a system designed for car drivers. This can be expressed in terms of further damage to the rims, lack of dynamic balancing, and a general bodging by those who are unused to the more specialised and delicate requirements of a motorcycle. A simple puncture could cost you a full day, and from two to several hundred pounds - can you afford not to use Puncturesafe?

Mike Fishwick - Technical Officer BMW Club.