At Cambrian Tyres we like to think that we have the most experienced sales team in the industry with over 230 years of experience between them, and if you’ve got a customer who wants to know about the most suitable tyre for their motorcycle our team are on hand to provide you with the expert technical support you need. In the July 2014 edition of Fast Bikes our very own Bryn Phillips has been discussing everything you need to know about tyre markings, so read on to find out what you missed….
The majority of riders know which tyre sizes are on their bike, but do they really know what a number such as 120/70 ZR17 M/C (58W) on a motorcycle tyre sidewall actually means?
The first section of this number indicates the tyre’s section width, in this case 120mm. The second number indicates the tyre’s aspect ratio or height expressed as a percentage of it’s width. In this case the aspect ratio is 70% of the 120mm width, making it 84mm. However, in order to allow the manufacturer to tune the tyre’s handling characteristics they are allowed to vary the stated width by +/- 4%.
Following the first two numbers are two letters. On a sports bike tyre these letters are usually “ZR”. The “Z” indicates the speed rating of the tyre, which in this case means it is rated above 149mph. The “R” denotes that the tyre is of radial type construction. If the tyre were of cross-ply construction the “R” would be replaced by a hyphen. The “17” denotes that the tyre is 17 inches in diameter whilst “M/C” means the tyre is for a motorcycle.
The “(58W)” indicates the load and speed indexes of the tyre. In this case the “58” denotes that the tyre is rated fora maximum weight of 236kg at maximum pressure, whereas the “W” represents 168mph. Please remember however that It is the “top speed” of the “slowest” tyre on your motorcycle which defines the maximum speed at which you should ride and which, if exceeded, risks tyre failure hence why you should replace a tyre with one of at least the same speed rating so that you don’t reduce the speed capability of your bike.
There are a number of different speed and load ratings, and their values in MPH and kilograms respectively are shown here.
The majority of tyres for sports bike contain the speed and load ratings in brackets. Brackets show that the tyre is capable of more than 168mph, whilst without brackets it would only be capable of speeds up to 168mph.
Next to, or near the size is the DOT code which indicates that the tyre conforms to the United States Department Of Transport regulations, and following this will be four digits molded in a separate rectangle. This is the date code, and it shows when the tyre was made. A tyre marked “2113” was made on the 21st week of 2013, and this information is very important as a tyre has a shelf like of around 6 years, although this can vary depending on how the tyre is stored with things such as temperature and humidity becoming a factor.
Tyre manufacturers also make their products in a variety of factories across the globe, so each tyre is stamped with a “Made in” location to denote country of origin. The majority of original equipment tyres on Japanese bikes are made in Japan, whilst most European built bikes use European built tyres. Replacement tyres will be identical in terms of markings, but are more likely to be built in Europe in order to reduce shipping costs although Bridgestone still make their radial tyres in Japan.
The final piece of information is the tyre’s name and model. Using the picture above this would be Bridgestone’s “Battlax S20” with a letter “F” after it. The “F” denotes the tyre is a front tyre, whereas an “R” would denote a rear fitment. On occasion manufacturers also make model specific original equipment tyres, and in this case a different letter may be used to signify that it is a special or specific tyre.
If you are in the motorcycle and two wheel tyre trade, Cambrian Tyres is the only account you need for a comprehensive range of tyres all backed by our team of experienced team of sales and technical advisers who are on hand to help you and your customer with the best independent support in the industry from the UK’s biggest two wheel trade only tyre distributor.
