WEAR TEST DATA for SELECTED BICYCLE ROAD TIRES
Compiled by Kerry Irons
New tire data (23mm unless noted). Thickness in 0.001 inches.
TIRE USAGE/WEAR DATA (all tires 23mm unless noted). Thickness in 0.001 inches.
(a) Tire not worn out but significant tread wear.
(b) Tire not worn out but significant aging (crazing, cuts)
(c) Tire worn so that casing just showing
(d) Tire worn so that casing showing extensively
(e)Tread separating from casing
(f) Ridden by one rider who felt it was worn out at 1500 miles, then ridden 1100 more miles before the casing started showing through tread.
All tires 23 mm marked size unless noted. F/R refers to whether and how much the tire was used on the front or rear wheel. Tires were weighed on a Mettler balance accurate to 1 gm. Thicknesses (tread and sidewall) are in thousandths of an inch, as measured with a micrometer accurate to 0.001". Tread thickness was measured in the center of the tread in at least 5 locations around the tire. Sidewall thickness was measured in at least two locations away from any lettering or labels. Since rubber can be compressed, an attempt was made to apply equal pressure (by feel) on each measurement. Variations in pressure could have caused thickness measurements to vary by 0.003 - 0.004". Vredesteins have softer tread than the Michelins or Contis, making it harder to get consistent readings.
If people are willing to send me their worn out tires along with some key data like rider weight, mileage, use on the front or rear, and riding style, this data base can be updated with results from the newest tires. If you're interested in contributing, e-mail me for details: irons54vortex at sbcglobal dot net.
Tire wear is proportional to rider power output, which is typically proportional to rider weight. The mechanism of tire wear (weight loss) is that small particles of rubber are abraded from the surface of the tire. Force per unit area grinds off the rubber, so higher rider power and lower contact area increase the rate of wear. For a given amount of power dissipation, lower speed (e.g. when climbing hills) means that the tire will wear faster because that amount of power is not spread over as large a total tire area in a given period of time. Higher tire pressure results in a smaller contact patch and faster wear.
Because power dissipation is mostly through the rear tire, most wear occurs on the rear tire, far more than can be explained by F/R weight distribution. Unless there is a LOT of heavy front wheel braking, a front tire can lose minimal weight due to wear, even after thousands of miles. Front tires may thin a little due to "cold flow" of the rubber on the casing. Front tires "age" due to environmental exposure, and so wear much faster if they are subsequently mounted on the rear. If a front tire accumulates significant mileage and is then moved to the rear, it will show about 1/3 faster wear than a new tire mounted on the rear.
If there is significant hard braking (e.g. lots of steep down hills) then front tires can wear due to power dissipation. Riders who do lots of intervals, "stomp" rather than "spin," corner hard, etc. will accelerate tire wear.
Road bicycle tires are worn out (casing threads beginning to show through the tread) when they have lost roughly 10% of their weight. Obviously, there are wide variations in tire construction which can shift rubber (and weight) to the tread or away from it, but for the lightweight road tire this general rule applies.
There is a significant difference in construction philosophy for different tire brands and models. For example, with nominally similar high performance tires, side wall thickness has been measured between 0.020 to 0.040 inches. For tires at similar weights, this can mean tread thickness (including casing) ranging from 0.030 to 0.050 inches for tires targeted at the same performance rider. The extra tread thickness, along with rubber compound differences, explains the significant mileage differences seen between brands and models of tire.
About the author:
Kerry Irons is a recently retired chemical engineer who has been an active cyclist since the mid-1960s. Irons began self-supported touring with high school friends in 1965, which led to a Michigan- Seattle-San Francisco solo ride in 1970, and a ride around Lake Huron in 1971. Since that time, Irons’ annual riding has averaged 7,000-12,000 miles, including commuting to work year-round and many roller miles in the darkness of Michigan winters. From 1980 to 1985, Irons operated Cyclo-Pedia, a mail order bicycle parts business. Irons rode tubular tires for nearly 30 years, but converted (along with his wife) to clinchers in 1998. This stimulated him to record tire wear data as a way to find better tires and to understand the issues of tire wear. Discussions with members of CyclingForum.com resulted in several riders sending worn out (and not so worn out) tires to Irons for measurement, the result of which is the information presented here