120/70 ZR17 F M/C TL SP A-Spec HWM What does it all mean Basil?
Decoding the sidewall of your motorcycle tyre.
Let's break down these codes, one step at a time....
WIDTH
The first number we find is the width of the tyre, this can be either a metric tyre in millimeters or an imperial size in inches.
120mm or 3.00 inches is straight forward enough
2.25 is 2 and 1/4 inches, 2.50 is 2 and 1/2 inches etc
4.10 means 4 inches plus 1/10th of an inch.
PROFILE / SIDEWALL HEIGHT
On imperial tyres, this number will not be present.
Metric tyres show the profile, or ratio. This is not something you can measure but it can be calculated.
Looking at the common front tyre size of 120/70 we simply calculate 70% of 120 to work out the side wall height in millimeters, 84mm in this case.
Taller side walls give a more cushioned ride at the expense of handling sharpness and corner stability.
A common question we get is if it is ok to change a rear 190/50 tyre to a 190/55, let's do the sums.
50 percent of 190 = 95mm
55 percent of 190 = 104.5mm ... which means the rear of your motorcycle would be 9.5mm taller and this would change the suspension geometry. For track use this may be advantageous but on the road it may make the bike too extreme and perhaps unsafe.
CONSTRUCTION
The next code can sometimes be hidden away, but just before the wheel size there will be one of the following codes...
| - | A hyphen means the tyre is X-Ply but there are some exceptions! Some X-ply tyres have a speed rating shown here instead, so instead of -17 you'd see either V17 or H17 (see more on speed ratings further on in this guide) |
| B | Bias-Belted |
| R or ZR | Radial tyres, with ZR being used exclusively for the very highest speed rated tyres. |
WHEEL DIAMETER
Nice and easy, it's just shows the size of wheel the tyre fits, in inches.
Yay, mixing metric and imperial at every opportunity.
eg. 120/70 ZR17 will fit a 17" wheel
150/80 r18 will fit a 18" wheel
2.75 -21 will fit a 21" wheel.
RATINGS
Tyres will also have a code in the sidewall information which can be very important indeed, it shows the load and speed ratings.
We have some quick charts to check....
A COUPLE OF EASY ONES...
We do occasionally get asked what does M/C mean on the sidewall? ... and right now you're either thinking 'what DOES M/C mean?' or 'ITS MOTORCYCLE OBVIOUSLY'... and now you're definately thinking the latter.
It is obvious, except in the places where it isn't obvious. It's easy for you and I ....... I work selling motorcycle tyres and you're here to buy motorcycle tyres (hopefully!) ... but most companies that make motorcycle tyres also make other kinds of tyre, car, van, lorry, cycle, e-scooter, tractor, JCB, aeroplanes, space shuttles, military vehicles, drag racers.. you get the idea.
An M/C marking is vital.
TT or TL means Tube Type or TubeLess.
A tube tyre tyre has to have a tube in it if you want it to perform as a tyre.
A tubeless tyre does not need a tube if mounted to a tubeless wheel.
A tubeless tyre can be used with an inntertube inside of it should your wheel or application require it.
We do not recommend the various methods of converting tube type wheels to run tubeless tyres. The various ways this could go wrong is not worth your life.
DATE CODE
its 4 numbers, the first 2 are a week number, the last 2 are a year
eg. 5223 means the tyre was made in the 52nd week of 2023
There is plenty more to talk about tyre dates, people worry too much about it but we'll look into that deeper soon!
LETS WRAP THIS UP WITH ... EVERYTHING ELSE THAT IS LEFT!
OK let's speed run all of the final codes you may see on your tyre....
Compound .... racing tyres can have compounds and different companies show this in different ways.
Soft, Medium and Hard are lovely.
SC1, SC2 and SC3 can be seen as soft medium and hard, as can K1, K2 and K3
End can mean Endurance, which is basically a Hard.
Soft/Med is ok for soft or medium terrains, Hard/Med is ok for hard and medium etc.
SP on Pirelli's denote a road biased compound of a race tyre, such as the Pirelli Supercorsa V4 SP
GT might mean it's a 'GT' tyre ... or it might not, you can read more about this confusing issue here
GT TYRES OR NOT GT TYRES, THAT IS THE QUESTION
A, E, M, F, G D .. oh heck there are so many 'spec' tyres.
A 'spec' tyre is made for a specific bike, it's an optimised version which has had extra research and development to be the best tyre if can be for that bike.
Sometimes it is essential that you use the correct tyre, sometimes it's ok to run the standard version, and sometimes they replace the standard version with one of the spec versions. It get's complicated but to simplify things....
Check your bike's handbook!
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