Complete guide to motorcycle tyres

Understanding your motorcycle tyres will help to keep you safe, extend the lifespan of your bike, keep down costs and make biking a lot more fun.

The law is very flexible when it comes to the tread wear on motorcycle tyres. The minimum is just 1mm, which it must have across ¾ of the tread area. The remaining ¼ must at least have visible tread. Many safety organisations, as well as the RAC and AA, agree that 1mm is far too low. Performance deteriorates markedly below 2.5mm and on heavier bikes the effects can come sooner. At Protyre our tyre professionals strongly recommend budgeting to change tyres when tread depth is between 2.5mm and 2.0mm.

The cost of changing sooner is lower than you might think. Tyres in good condition are often more fuel efficient, so your expenditure on petrol and oil will be lower; they also put less strain on your brakes and traction. Logically then, good tyres reduce the long-term overheads of repairs and replacement parts.
 
Mopeds and scooters under 50cc are exempt from the 1mm tread depth law, but the same reasoning applies, changing tyres earlier is better for the machine and it’s rider.

Your user manual is the place to look when you need to identify the right kind of tyres for your particular bike. The main parameters are their width, aspect ratio, speed rating and maximum load. Remember that on nearly all bikes the rear tyre is bigger than the front. Tyres with the same specifications from different tyre makers are often a little different, but don’t depart from the recommended specifications.
 
The width, aspect ratio, speed rating and maximum load details are also printed into the rubber on tyre sidewalls. The format varies a little, so for example 180/55 - 17 M/C 73 VR means the same as 180/55R17 (73V280). In both examples:

• “180” is the tyre width in mm

• “55” is the aspect ratio, the height from the rim as a percentage of the width

• “17” is the rim size in inches

• “M/C” is usually present to confirm it is a motorcycle tyre

• “73” is the load rating

• “R” denotes that the construction is radial

• “V” is the speed rating

• “280” in the second example is an interpretation of the speed rating in Km/hr

Tyre markings also provide other useful details, including:

• A date code consisting of two digits for the week and two for the year

• Whether it is tubed or tubeless

• An arrow to show the correct fitting direction, as motorcycle tyres are one-way only

• Finally, front and rear motorcycle tyres are radically different so often they also state if it is a front or rear tyre

Some parameters don’t need to match exactly. For example, the speed code denotes the maximum safe speed the tyre can take, so there is no problem with fitting a higher speed-rated tyre. Your manual denotes the minimum rating based on the upper potential of your engine. However, fitting a higher speed rating tyre won’t make you go any faster though and may cost more. Likewise, the load rating, you can fit a stronger tyre but never a weaker one.
 
Depending on the bike, it is sometimes possible to swap in another wheel with a larger rim and lower aspect ratio, or vice versa, providing the total diameter remains the same. Before you consider this, check with the motorcycle manufacturer and with your insurance company. Generally speaking, we do not advise it and some garages are reluctant to do it.
 
Some riders like to fit wider tyres, especially at the rear. Again, you need to confirm this with the manufacturer and your insurer. It is very unlikely to improve performance, steering or fuel economy although we have to admit it looks great on big cruisers. Be aware that you might need far reaching modifications to avoid issues with the gearing or speedometer, or to avoid contact with a swing-arm or fender. A handful of motorcycles have been designed to support wide wheels, most have not.
 
Some bikes, mostly classics and scramblers, still use cross-ply tyres. A few heavy tourers use bias-ply. The majority of bikes should stick to radials. Never ever mix cross-ply and radials on the same bike, although a few heavy tourers are actually shipped with a bias-ply at the front and a radial behind. If your bike wasn’t designed for it don’t do it.

Although we strongly advise sticking with the recommended tyre specifications, you do not have to stick with the original “OE” tyre brand, or with a manufacturer’s brand recommendation, which is often commercially motivated. This leaves you with plenty of choice when selecting new tyres. The ideal tyre does depend on the bike, but it depends even more on the rider, the roads, the weather where you live, and the way you use your bike.

Broadly speaking, there are tyres designed for summer or for winter, long distance cruising or off-roading, city commuting or racing, for extra heavy loads, for long durability or fuel economy. Some are more comfortable; others give more road-feel and of course some cost more and some less. You are the best person to decide which features are important. That is why the Protyre website has been designed to show you the broadest possible range. All our local garages are well stocked, and our tyre professionals are happy to provide free advice at any time.

Bridgestone have one of the strongest reputations in motorcycling tyres and are often factory-fitted. Without doubt their premium offering is the Battlax range. The entry level tyre is the Bridgestone Battlax BT-016. You could also look at the excellent S22 which is suitable for both road and track, the cutting-edge T31 sports-tourer, the A41 “adventure tyre” and the even more adventurous Bridgestone Battlax Adventurecross AX41. This model has increased rigidity for greater off-road use but plenty of performance and durability on-road too.
 
Other star performers include the Michelin Pilot Power and Pirelli Diablo Lasso III. There are also good offerings from Dunlop and Avon.