Motorcycle tyre markings for numpties

A guide to typical motorcycle tyre markings for the info hungry newbie…

So you need a new tyre but don’t know what to ask for in the shop. That’s ok, any tyre place will look your bike up on their system in two minutes, sell you a new tyre of the correct type and take your money while you read an unsanitary copy of Bike magazine with yet another adventure bike shootout from three years ago and drink piss weak tea from a machine. Yep, you’ve been there too. The last stand of PG Tips and the world’s biggest repository of unwanted copies of Bike awaits us all.

But if you want to use the internet’s magic ability to save yourself some dollar with a price finder site like blackcircles.com or just want to feel smug while you peel back the pages of Bike with a pair of tweezers and realize you actually know more than some journalists, you’ll need a bit more in the tank than ‘my tyres are black and round’ (though this is definitely a good starting point).

So let’s start with the very basics. With a few exceptions on the smallest bikes and some scooters, front and rear tyres are made differently and are marked as such.

Here’s the front:

front rotation

the rear..

rear rotation

…and that’s about as easy as the markings get I’m afraid.

Oh apart from all those arrows, also hopefully self-explanatory.

directional arrow

Except for some of the retro excreta appearing on Instagram-imprisoned café racers these days, proper motorcycle boots are now designed to rotate in a particular direction. The directional arrow always signifies forward movement of the bike because tread design’s moved on from the Avon Speedmaster of yore (I salute thee oh everlasting Avon Speedmaster) and has been computer modelled to both disperse water efficiently and to deform in a certain way as you lay down power – and what computer guy says, goes. If tyre rotation is accidentally reversed, the tread won’t channel water away from your tyre’s contact patch on the road as efficiently and if this befell a Suzuki Hayabusa the world would inevitably be forced into reverse like at the end of Superman 1 and time forever erased. (And now I’ve placed that nagging doubt in your mind, I’d give odds on you popping out to the shed to check to see yours are on the right way around).

All ok? Now for sizing. What most people see on bikes these days is a confusing mess of numbers on the tyre wall:

size front

120/70/ZR17. This is the tyre size which you’ll need to type into blackcircles.com in your hunt for a bargain. Just to properly confuse things, the first figure is in millimetres, the second a percentage and due to tradition, the last is in good old British inches – the kind that got us through the war. Good system eh? I never said motorcycles were logical.

We’ll get to that ZR in a moment but for now let’s explain the numbers. The first one refers to the tyre’s width, which is 120mm. The second figure refers to the tyre’s height as a percentage of its width. Here the figure is 70, so that’s 70% of 120mm, which if you work it out (on the er, internet) is 84mm. Finally the tyre’s fitted to a 17” rim. Not so bad eh?

And here’s the rear. 160/60/ZR18.

size rear

Note the rear is always wider as it takes more direct weight and must put up with the accelerative and decelerative effects of the engine and drivetrain. Following form, this tyre is 160mm wide, is 60% of 160mm high which is 96mm (thanks again, internet) and it’s fitted to an 18” rim. As easy as Pi.

Now to those letters.

Z speed rating

The letters you see near to the tyre size have significance and can appear on the tyre in different ways. However you find yours written, one letter (circled) will refer to the tyre’s indicative maximum design speed rating which for obvious reasons must meet or exceed your own bike’s. Even if you never intend to ride to the shops at 168mph, your tyres must still be appropriate for the bike, so no cheaping out. Here’s a list of possible code letters you might see:

B 31 mph
J 62 mph
K 68 mph
L 75 mph
M 81 mph
N 87 mph
P 93 mph
Q 99 mph
R 106 mph
S 112 mph
T 118 mph
U 124 mph
H 130 mph
V 149 mph
Z 150> mph
W >168 mph
Y >186 mph

That makes our Z rated tyres in the example suitable for ‘more than 150mph’, which I can tell you despite a valiant effort on the Autobahn last week is definitely faster than the BMW these tyres are attached to will go.

Now to the second letter code.

radial marking

The R afterwards simply means radial – a common type of tyre construction for higher performance modern motorcycles. Others you see might be ‘-‘ (cross ply – the old standard) or bias belted (B) instead.

Radial tyres are constructed from cords laid at 90 degrees to the direction of travel reaching the shortest distance from edge bead to edge bead before being bonded with rubber. The cords simply provide strength and define how flexible the casing is – an important factor in the feel of a motorcycle.

radial

They’re commonplace now, are lighter than old style cross plies with their heavy side walls, heat up less and don’t ‘grow’ so much at speed. According to German tyremaker Continental, a radial tyre at 131mph will expand around 2mm from the centrifugal forces it’s subjected to. An old style cross ply adds around 2cm at the same speed – yike!

This casing also tells us it is produced from two plies (layers) of Polyamide and has a protective outer belt of Aramid.

polyamide aramid

These are not places hobbits live but modern synthetic fibres similar to Kevlar. Aramid in particular is lighter but as durable as the steel wire belts which it replaces and is heat resistant. Why not just use heavier steel? Well a lighter tyre is good for two important reasons – there’s less un-sprung weight for your suspension to carry and a lighter wheel takes less energy for your engine to turn. Good news all round.

Tubeless. (You may also see TL – tube type tyres are marked TT) Tubeless is the modern standard for road bikes.

tubeless

Tubes are no longer used to carry air in the majority of road bikes. Like car tyres, motorcycle tyres are now manufactured to snugly seal themselves onto air-tight wheel rims and stay up all by themselves. This is why you can’t change them yourself unless you’re a desperate maniac.

Why tubeless tyres are better: Tubeless tyres are safer than tubed tyres for road bikes when the inevitable puncture happens. Due to their inherent strength, tubeless tyres tend to deflate slowly and in a controlled manner once something punctures them like a nail or a screw. They can even stay up without you knowing there’s a nail in there at all until the head wears off and you miss it entirely. And if you do find it, you can get the hole plugged easily. The same can’t be said for tubed tyres. Once a spike goes through a thinly stretched tube under high pressure, there’s a high possibility that it’ll deflate catastrophically just like a balloon does with a pin. This happened to me on a tubed bike once. I did not enjoy it.

Here’s the manufacturer.

michelin brand

There are loads of brands out there and the level of tyre nerd-dom in motorcycling is legendary – everyone has an opinion about that tricky balance of wear rate, grip and price and whether one budget brand is actually as good as another premium one. For road riders it’s a case of trawling internet forums to help you get an overall picture of whether a particular tyre suits your bike and style of riding with recommendations from other riders. Some of them will even be knowledgeable.

Bike-specific tyre fitters are good source of knowledge and know what’s popular too. If you’re like me you’ll do this once, find a tyre you like and stick with it. In case you’re interested, I prefer Michelin Pilot Road 3 on heavy tourers, Bridgestone Battlax on mid size roadsters and sport tourers and Bridgestone Trailwings on my dual sport bike. All are long lasting as opposed to ‘sticky’ as I’m an incurable tightwad.

On to maximum load rating (the gross weight each tyre may carry) and the maximum pressure it can take.

max load

Note this is not a recommended running pressure as some assume, just an absolute design maximum for the tyre. It goes without saying that your total load includes fuel, passengers and sandwiches and you mustn’t exceed it.

TIP: If you are brand new to the world of motorcycle tyres (and I do mean brand new) then check my tyre pressure article for more a quick how-to.

DOT markings. Michelin refer to DOT markings as the birth certificate of your tyre, and I can’t improve on that. If there’s a tyre recall for safety reasons and it comes from a particular manufacturing plant, you’ll need to know this.

DOT markings

Here we see DOT HBCW 00HX 4913. DOT stands for Department of Transport and signifies the tyre conforms to the United States & Canada’s DOT regulations. The extra letters signify the manufacturing plant code (HB) and optional size code (CW). 00HX is a dimensional code and most importantly the four numbers in a rectangle signify when the tyre was made. This one was made in the 49th week of 2013. Manufacturing dates are important as tyres can sit on the shelf for about 6 years before they start to go off (though this depends on whether they were stored out of natural light and in ideal conditions of temperature and humidity). Now I bet you go off to see how old your tyres really are.

M/C (58W) This is a load and speed rating.

MC58W

M/C unsurprisingly means motorcycle and stops inattentive techs accidentally fitting them to cars. 58W is another code and refers to the load and true speed rating of the tyre. 58 translates to 236kg at maximum allowable pressure (you can find these codes explained on each tyre manufacturers website). The W refers to the true speed rating of the tyre which if you refer back to the list at means it’s 168mph rated.

Hold on a minute! Why’s this tyre also rated Z as we’ve already seen? Because the Z rating is an indicative rating, telling us the tyre is safe ‘somewhere beyond 150mph’ is why. The W gives the true speed rating – in this case up to 168mph. High performance tyres like W or Y rated ones can also be confusingly be marked in this way. The Z simply indicates “over 150mph” and the second marking indicates the true design maximum. Basically the highest value printed on your sidewall wins.

“Two Compound Technology”. As road bikes are ridden for 90% of the time upright in a straight line no matter how tasteless your leathers and how iridium your visor, it makes sense that the central portion of the tyre is durable, resistant to overheating and wears relatively slowly.

dual compound

As the other 10% of your time will be taken up in life-affirming cornering, premium manufacturers decided in their wisdom to make the edges (or shoulders) of their sports and touring tyres from a grippier rubber compound to the hard wearing central portion. This is the essence of dual compound tyre technology.

The rubber of this shoulder compound is softer (and so less durable), but as you hardly use the shoulders this matters not. That softness means the rubber heats up quicker and reaches its optimum grip level quicker for when you need it in the twisties. Dual compound tyre technology like this is commonplace nowadays and represented a quantum leap forward in terms of tyre design when it came out.

That’s all the interest I can wring out of tyre walls for now. If you read this far, congratulations. Perhaps consider how you’re spending your free time. Really, you read 2000 words about tyre wall markings? I don’t know who that reflects on worse. You for reading it, or me for writing it.

Absolutely Final Hassle Avoidance Tip: If you’re a newbie this probably won’t apply to you but if you get into the habit of taking loose wheels to tyre shops because you don’t trust the fitters to remove and refit the wheels properly (one unfortunate experience a lifetime’s habit makes) make sure they can still understand which way your wheels turn. I chalk the old tyres or put a piece of insulation tape on the rim with a directional mark and smiley to guide the fitter in the least patronising way I can manage. This is important as some bikes like one of mine have drive trains on the opposite side from ‘normal’ (a BMW F650 Funduro with the Austrian built Rotax motor) and this could easily fox your average fitter who may assume between sandwiches that all bikes are like those common as muck Japanese ones with the drive sprocket on the left. Result? A tyre carefully put on backwards. Happened to me – makes for a great awkward moment in the shop.

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