BMW touring bikes

 

 

 

 

 

Motorcycle Tyres

 

Introduction

In all ways bikers take their motorcycles more to the extreme than the average motorist. There is also bigger variety available to the biker who wants to replace his tyres. For this reason, selecting the correct tyres for you motorbike is more involved and should only be undertaken after a lot of research. Fortunately the Internet has a lot to offer from input from manufacturers and bikers themselves.

Five Characteristics

Generally tyres five different characteristics i.e. their grip in the dry, their grip in the wet, off road handling, tyre noise and expected kilometres. 


The Tread

A common misconception about tyres is that the deeper the tread, the better the tyre will grip the road. This is incorrect. It is the rubber that is exposed to a good surface that keeps the vehicle controllable. The deep tread is simply somewhere for the water/mud/sand/crud to go when the tyre travels on a imperfect surface. If there were no tread, the crud would come between the good surface and the tyre. The vehicle would cease to be in contact with the road and the result would be loss of control (aquaplaning in the case of water)

Hard and Soft Rubber

Tyres are always a compromise between the ability to grip the road and longevity. The softer and more sticky the rubber compound the better it grips but it will not last more than a few thousand kilometres. The harder the compound, the less it grips but the longer it will last.

Pressure

Tyre pressure too is a compromise. The lower the pressure, the better the tyre is able to flow into the dimples in the road surface. At speed however the friction generated causes dangerous levels of heat. Under inflated tyres are also prone to punctures and shortened life span. Only under inflate when travelling over loose desert/beach sand (reduce pressure by 30% for tubeless and 40% for tubed)

Over inflated tyres do not grip as well due to their lack of flexibility. Only over-inflate when covering very rough terrain with large rocks and stones (Increase by 10%)

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Tyre patterns and design

There is a huge variation in tyre patterns and design.

Broadly tyres divide into road, enduro (trail) and off-road (scrambler). You do not take slick track tyres off-road and aggressive off-road tyres stay exactly there i.e. off road!. Enduro types are an attempt to make a tyre with reasonable characteristics of both but must not be pushed to the extreme in either environment as they are in all ways a compromise between two incompatible extremes.

Within these three categories tyres are again divided into hard and soft compounds. Hard, giving longevity and soft, offering extra traction but fewer kilometres.

The maximum speed rating and maximum load bearing characteristics differs from tyre to tyre as does width, profile and tread pattern

Road Tyres

On the extreme end of the road tyre spectrum there are the fat, smooth, slick tyres for sportbikes capable of more than 200km. These road/track tyres place maximum rubber onto the road surface and have only the smallest treads to funnel away small amounts of water that may be on the road. Track tyres are made of a softer compound than their road counterparts.

Sportbikers should take special note of the 'Maximum Load Rating' and 'Maximum Speed Rating under Load' of their selected tyre before putting a passenger on the pillion seat.

The tread in a sport touring tyre is wider, deeper and there is more of it. The compound is harder and the maximum load rating is higher.

Cruiser tyres have a higher maximum load rating to cope with the biker size of the motorbike.

Off Road Tyres

Off road tyres vary. On the one extreme the separate blocks of rubber are big. The more aggressive the tyre looks the more suited it is to very rough conditions but the poorer the performance on hard, wet road surfaces. One of the reasons for this is the small amount of  rubber that actually comes into contact with the road surface. They are also noisy and affect the top-end speed due to the increase in road friction (therefore going 200km on a breakfast run is not an option!).

The wider and bigger the tread between the blocks of rubber, the more suited it is to thick muddy conditions. The more closely packed the blocks of rubber are, the more suited it is for sand and gravel.

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Enduro (trail) Tyres

Somewhere in the middle between road and off road tyres comes the trail tyre with large flat blocks of rubber closely packed together in order to get more rubber onto the road. They offer reasonable performance on road and off road. They are not too noisy and the rubber compound is not too soft.

Issues when choosing a tyre

Even when you have chosen the right type of tyre there are still a number of ratings that apply. Explore these in detail with your dealer.

  1. Will the tyre fit your particular rim?

  2. Can the width of the tyre be accommodated by your motorcycle frame?

  3. What is the maximum speed rating for the tyre?

  4. How is the maximum speed affected by having a pillion passenger or by heavy touring gear?

  5. What is the maximum load for the tyre?

  6. What is the recommended and maximum tyre pressure?

  7. How does the tread width and tread depth compare with comparable tyres by other manufacturers?

  8. Is the tyre essentially a soft or hard rubber compound?

  9. Is the tyre a radial or a bias ply tyre?

Tubed and Tubeless

The tyres that one fits are either tubeless or tubed. This is dictated by the construction of the wheel rims in the first place and the tyre itself in the second and the nature of the riding you do. Naturally, rims with wire spokes that go right through the rim need tubes while alloy rims that are cast as a single unit can accept tubeless tyres.


Tubed tyres and their associated spokes rims are hardier e.g. one can deflate the tyre to a greater extent when travelling over thick desert sand. They can also tackle tough off road conditions with stones, rocks and potholes as the spokes wheels can handle this type of abuse better than alloy wheels.

Tubed tyres are seldom speed rated over 200km per hour as they generate more heat than their tubeless counterparts.

Tubeless tyres and their light alloy rims are not well suited to tough conditions as they loose their shape and the tubeless tyres can no longer seal themselves against the rim. One of the big advantages of tubeless tyres is the ease of repair when one has a puncture as the tyre can stay on the rim during the repair process (naturally this does not apply to side wall punctures). They are also safer at high speeds and can be speed rated in excess of 300km per hour.

Tyre ratings

Every tyre has a series of rates e.g. speed, load etc. How to read them is a big topic. For a full explanation of tyre ratings see the Bridgestone web site at Bridgestone.com. The site Sidcupmotorcycletyres.co.uk is a site where bikers give their feedback on various tyres. (See links page for both of these sites)

Pairs of Tyres

Motorcycle tyres come in pairs - the particular model has a front wheel version and a partnering back wheel tyre to go with it.

Compromise

Even within each type of tyre the name of the game is compromise. In fact the only time you will really know whether your tyres suit your overall needs is when the ‘tacky hits the track/road/trail’ so to speak! Guys who own dual sport motorbikes may even find that you will have to purchase two sets of tyres e.g. one set for town use and one for their annual trek into the bush or desert.

Examples

Using the Bridgestone range of tyres here are examples of the different types.

Bridgestone Tyres

bridebt45f.jpg (14012 bytes) BT45F

Sport Tyre

   
bridebt56r1.jpg (8560 bytes) BT56R

Sport Tyre

   
bridebt020f.jpg (14788 bytes) BT020F

Sport Touring

   
brides11f.gif (8597 bytes) S11F

Sport Touring

   
brideg703.gif (5693 bytes) G703

Cruiser Tyre

   
BRidetw25.jpg (14944 bytes) TW25

Dual Sport (Enduro)

   
brideed11f.jpg (5237 bytes) ED11F

Serious Off Road Tyre

   
bridgem_25.jpg (26964 bytes) M25F

Thick Mud Tyre

With complements from flamesonmytank

 

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