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RoadBikeRider newsletter on tire wear
The RBR newsletter today had an interesting tidbit about tire wear:
----------------------------------------------------------------------------- 2. Jim's Tech Talk: Tire Wear II In newsletter No. 147, I answered a question about why tires wear faster on the rear wheel than the front. That brought an e-mail from Kerry Irons of Midland, MI, who has made a hobby of studying tires for 6 years. His findings shed valuable real-world light on why tire treads deteriorate at different rates. So this week I'm using my space to share his findings with you. Kerry, a 54-year-old retired chemical engineer, has analyzed more than 50 new and used tires. He measures tread and sidewall thickness, and records rider weight and miles ridden. Other roadies help by sending him their used tires and feedback. Kerry weighs 180 pounds and rides 6,200 miles a year. He also tracks tire wear on the bike used by his wife, Mary, who weighs 125. Here's a summary of Kerry's observations: ---Tire wear is roughly linear with rider weight. ---Tire location is the major factor in tire wear. Identical tires will have significantly different wear front and rear, far more than can be explained by a rider's front/rear weight distribution. ---Even after thousands of miles, front tires essentially lose no weight due to wear, although they do thin a little because of mechanical spreading ("cold flow") of the rubber on the casing. ---Exception: If there is significant hard braking (lots of steep downhills), then front tires can wear due to power dissipation. ---Riding a tire for significant mileage on the front and then switching it to the rear reduces its rear mileage somewhat compared to putting a new tire on the rear. The front tire "ages" due to environmental exposure, resulting in about 1/3 faster wear once mounted on the rear. ---The reason rear tires wear out so much faster is power transmission through the tire. Riders who stand, sprint frequently, corner hard and so on are likely to significantly accelerate rear tire wear. It is likely that riders who "stomp" the pedals rather than "spin" will wear rear tires faster. ---Tires are worn out when they have lost roughly 10% of their weight. There are variations in tire construction that can shift rubber (and weight) to the tread or away from it, but this general rule applies to lightweight road tires. ---For roughly 60,000 miles, my wife and I have found that flats spread uniformly over tire life. Our experience shows no correlation of mileage and flats, but any given tire flats so infrequently that the statistics are fairly sketchy. ---There is a significant difference in tire construction philosophy. For example, Continental GP and GP 3000 sidewalls are about 0.020 inches thick, while the Continental GS is 0.040 inches. Michelin Axial Pro sidewalls are 0.030-0.033 inches, while the Axial Super Comp is 0.042 inches. Some would argue that these differences explain the "fragile sidewall" reputation that Continentals have, though my wife and I have never experienced a Conti sidewall failure. ---A Continental GP has 0.045-0.055 inches of tread, while a Michelin Axial Pro has 0.030-0.040 inches. The extra tread thickness, rather than a rubber compound difference, explains the Conti's greater mileage. ---Within a brand, tread compound affects durability. A Continental GP3000 has about the same tread thickness as a Conti GP. But the GP3000 wears out significantly faster, presumably due to much lower carbon black content in its tread compound. After all this, what's Kerry's tire choice? He says he and his wife ride Continentals almost exclusively. ----------------------------------------------------------------------------- All very interesting, but how about the most important piece of information -- how long did all these different tires last? If anyone knows Kerry Irons, perhaps we could convince him to publish his findings here (or somewhere else we can all read it). Matt O. |
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RoadBikeRider newsletter on tire wear
In article ,
"Matt O'Toole" wrote: The RBR newsletter today had an interesting tidbit about tire wear: ----------------------------------------------------------------------------- 2. Jim's Tech Talk: Tire Wear II All very interesting, but how about the most important piece of information -- how long did all these different tires last? If anyone knows Kerry Irons, perhaps we could convince him to publish his findings here (or somewhere else we can all read it). Matt O. It would also be interesting to see mileage comparisons between different widths of the same tire. For example, I've used both 23mm and 25mm GP 3000, and the tread on the 25mm is MUCH thinner than the 23 mm. |
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RoadBikeRider newsletter on tire wear
All very interesting, but how about the most important piece of information --
how long did all these different tires last? If anyone knows Kerry Irons, perhaps we could convince him to publish his findings here (or somewhere else we can all read it). I saw that he posted more elsewhere - i HOPE he doesn't mind wider distribution: New tire data (23mm unless noted) Weight Tread thickness side wall thickness Vredestein Fortezza TriComp 262 109-115 26 Vredestein Fortezza 25 280 NA 25 Conti Grand Prix 3000 232 128-129 23 Conti Grand Prix 220-222 115-122 22 Conti GS 275 NA 40 Michelin Axial Pro ~240 NA 31 Michelin Axial Pro Winter 227 NA 31 Michelin HiLite BiSynergic 260 NA 31 Michelin HiLite Comp 20 260 106-112 46 Michelin HiLite Comp ~280 NA 39 Michelin BiSynergic ~240 NA 33 Michelin Axial SuperComp 240 NA 42 Michelin Axial Pro 225 95-99 30 IRC Paper Lite Plus NA NA 21 IRC Metro 26x1.5" 540 NA 23 Specialized Armadillo 26 380 NA 40 Panaracer Pasela Comp 26x1.25 240 NA 21 Vittoria Twin Techno Green 230 80-87 30 Vittoria Twin Techno Orange 25 (measures 23) 270 120-127 33 Clincher Tire Note mileage rider wt (lb) Wt. % Wt loss Tread thickness Vredestein Fortezza 2 ~2000R 180 234 11 66-74 Vredestein Fort. Tri Comp 4 6420F 1950R 180 236 10 59-65 Vredestein Fortezza 25 4 900 F 1200R 180-215 255 8 47-62 Vredestein Fortezza 2 ~2000R 180 234 11 66-74 Vredestein Fortezza 25 2 ~715R 195 265 5 69-74 Vredestein Fortezza 25 2 ~1940R 175 259 8 73-82 Vredestein Fortezza 2 1400R 175 225 14 78-86 Conti Grand Prix 3000 4 5050F 1300R 180 217 6 69-77 Conti Grand Prix 3000 4 1300F 2950R 180 203 12 66-75 Conti Grand Prix 3000 4050F 180 224 3 105-110 Conti Grand Prix 3000 5,6 4000R 190 194 16 66-72 Conti Grand Prix 3000 20 2 2640R / 2350F 150 178 23 82-88 Conti Grand Prix 3000 4 3380R / 3380F 142 192 17 63-70 Conti Grand Prix 3000 4 3380R / 3380F 142 191 18 65-73 Conti Grand Prix 3000 blue 5 3380R / 3380F 142 191 18 65-73 Conti Grand Prix 3000 gray 5 3380R / 3380F 142 191 18 65-73 Conti Grand Prix 3000 blue 5 3380R / 3380F 142 191 18 65-73 Conti GP 4 9500F/ 4500R 124 198 10 70-77 Conti GP 3 5045F/ 4068R 180 192 13 71-76 Conti GP 4 6070R 185 199 10 64-78 Conti GP 4 ~ 9500R 125 194 12 63-78 Conti GP 3 ~ 9500F 125 222 0 111-120 Conti GP 4 3170F 5045R 185 191 13 68-85 Conti GS 7 ~ 1500R 190 243 12 85-90 Conti GS 7 1100R 185 235 15 68-75 Michelin Axial Pro 5,6 2100R 190 209 13 54-56 Michelin Axial Pro Winter 5,6 2000R 180 205 10 54-56 Michelin HiLite BiSynergic 4 ~2300R 150 225 13 64-67 Michelin HiLite Comp 20 4 1730R 175 250 4 73-80 Michelin HiLite Comp 2 600R 195 243 13 70-75 Michelin BiSynergic 3 7940F 185 232 3 73-81 Michelin BiSynergic 4 7940F 2230R 185 220 8 52-58 Michelin Axial SuperComp 6 2160R 175 214 11 59-65 Michelin Axial SuperComp 2,6 3540F 175 217 10 71-76 Michelin Axial Pro 1 0 n/a 225 6 95-99 Michelin Axial Pro 4,6 3850F 185 221 8 70-72 Michelin Axial Pro 20 5,6 3500R 185 190 21 52-66 IRC Paper Lite Plus 5 2000R 150 175 ? 36-51 IRC Metro 26x1.5" 2 1100R 195 535 1 102-106 Specialized Armadillo 26 2 1100R 195 350 8 72-85 Panaracer Pasela Comp 26x1.25 2 1000F / 300R 195 231 4 93-98 Vittoria Twin Techno Orange 25 (actually 23) 4 4200R 180 245 9 68-75 Tubular Tire Note mileage Size rider wt (lb) New / used wt Tread thickness side wall thickness Vittoria Tour TSD 1 ~ 500F 23 185 273/273 78 25 Foxonall (Clement) Citerium 2,6 1690F / 1135R ~23 160 250/246 NA NA Clement Citerium 2 2025R ~23 160 252/235 NA NA Clement Citerium 2 2775F / 1310R ~23 160 252/237 NA NA Conti Sprinter 250 2,6 2475R 22 160 280/262 NA NA Inner tube wt (gm) Thickness Vittoria tubular inner tube 38 Michelin Ultralight tube 69 38 Michelin Airstop tube 43 Kendra tube (Nashbar ultralight) 74 41 Notes: 1 New tire. 2 Tire not worn out but significant tread wear. 3 Tire not worn out but significant aging (crazing, cuts) 4 Tire worn so that casing just showing 5 Tire worn so that casing showing extensively 6 Tread separating from casing 7 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 - Michelins have significantly thicker sidewalls than Contis or Vredesteins, while the Contis have significantly more tread rubber than the Michelins. A new Axial Pro's tread is not much thicker than the Conti GP when the Conti is worn out. The weight of the Michelins is in the casing rather than the tread. - Weight of a new Michelin BiSynergic not known (around 240 gm?). The manufacturers listed weight for the Michelin Axial SuperComp is 240 gm. - Inner tube thickness measurement is "double" (two layers of tube). - F/R refers to whether the tire was used on the front or rear wheel. - Rider weight is in pounds. - Tire and tube weights were determined on a Mettler digital balance accurate to 1 gm. - Thicknesses (tread and sidewall) are in thousandths of an inch measured with a micrometer accurate to 1 thousandth of an inch. Tread thickness measured in the center of the tread in at least 5 locations around the tire. Sidewall thickness measured in at least two locations away from any lettering or labels. Due to the fact that the rubber could be compressed, an attempt was made to "tighten" the micrometer to the same degree (by feel) on each measurement. Variations in "tightness" could have changed thickness measurements by 3-4 thousandths. Vredesteins have softer tread than the Michelins or Contis, so it was harder to get consistent thickness readings. - Michelin Airstop tube was patched, so no weight was taken. - After extensive use on the front , tires may be cracked and crazed with numerous tread cuts, but do not show significant thinning of the tread or weight loss. - Vittoria information is on a relatively low cost tubular tire (nominal 270 gm, $25), cut open to take the measurements. There was no visible tread wear on the ribbed center section Observations (biases are strictly the observer's!) 1. Tire wear is roughly linear with rider weight. 2. Tire location is THE major factor in tire wear. Identical tires significantly different wear front and rear, far more than can be explained by F/R weight distribution. Even after thousands of miles, front tires essentially lose no weight due to wear, although they do thin a little due to "cold flow" of the rubber on the casing. Riding a tire significant mileage on the front and then switching to the rear, reduces rear mileage somewhat compared to mounting a new tire on the rear. The front tire "ages" due to environmental exposure, resulting in about 1/3 faster wear once mounted on the rear (see the Conti GP with 5K miles front/4K miles rear vs 6K miles rear for a new Conti GP on the rear, same rider). 3. The reason rear tires wear out so much faster is power transmission through the tire. If there is significant hard braking (lots of steep downhills) then front tires can wear due to power dissipation. Riders who stand, sprint frequently, corner hard, etc. will likely significantly accelerate rear tire wear. Presumably hard cornering would wear front and rear tires roughly equally (affected by F/R weight distribution). It is even likely that riders who "stomp" rather than "spin" will wear rear tires faster. 4. Tires are worn out 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. 5. My experience (me at 180 lb. and my wife at 125 lb.) shows no correlation of mileage and flats, but any given tire flats so infrequently that the "statistics" are fairly sketchy. For roughly 100K miles, my wife and I have found that flats spread uniformly over the tire life. 6. There is a significant difference in construction philosophy for different tires. The Continental GP and GP 3000 side walls are about 0.020 inches thick , while the Conti GS are 0.040 inches. The Michelin Axial Pro side walls are 0.030-0.033 inches, while the Axial Super Comp are 0.042 inches. Some would argue that these differences explain the "fragile side wall" reputation that Contis have, though my wife and I have experienced no Conti side wall failures in over 100K "tire miles". 7. A Conti GP has 0.045-0.055 inches of tread, while a Michelin Axial Pro has 0.030-0.040 inches. The extra tread thickness, rather than rubber compound differences, explains the greater mileage with the Conti. Within a brand, tread compound does effect durability - a Conti GP3000 has about the same tread thickness as a Conti GP, but the GP3000 wears significantly faster, presumably due to much lower carbon black content in the GP3000 tread compound. |
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