As National Motorcycle Week kicks off riders are being warned of the dangers that continuous upright riding on fast straight routes can do to their bikes’ tyres.
Long journeys on motorways can cause the meeting of the tyre’s sidewall and tread to ‘square-off’, which gives a feeling of loss of grip when the bike is used on winding roads. Often on long journeys motorcyclists switch from the motorway to fast A- and B-roads, without knowing their bikes’ handling is compromised.
Gary Hartshorne, motorcycle tyre technical specialist for TyreSafe, says the squaring-off phenomenon will always affect bike tyres because of their design, but if the bike is being constantly ridden on winding roads squaring-off will take longer to occur, meaning extended tyre life.
The type of journey covered isn’t the only reason for squaring-off, as other factors can have an impact: “It also depends on the materials used, the compound of the tyre and the original profile of the tyre when new. Some tyres have a flatter profile to start with while others can be very pointy. The more ‘pointy’ they start out as, the more the squaring-off will become apparent as the tyre gets older,” Gary Hartshorne says.
Tyre pressures can also affect the squaring, with both under- and over-inflation causing problems, as Gary Hartshorne explains: “If tyres are underinflated this will cause squaring off, as would running them overinflated, but then the width of the ‘squared band’ around the tyre would be narrower as the contact patch would be narrower in the first instance.
Tyre design means there is no cure for the squaring-off phenomenon, but once they’re aware it might happen, riders can adjust their riding accordingly.
“It’s important that motorcyclists make allowances for any unusual handling characteristics their bike might show when they leave the motorway,” says Karen Cooke, director of safety for the Motorcycle Industry Association. “Keeping tyre pressures at recommended levels is one way to ensure safe riding, as is rider awareness.”