I have a 2005 RC51 with maybe 2500 miles on her. I'm in the tire industry for cars and trucks, but have no clue regarding motorcycles. At 2500 miles, obviously the tires have tons of tread left on them, but when should I replace them because of age? Is there a specific time when I should pull the stock tires off because of safety issues like dry rotting?
The stock tires "look" good, no visible signs of sidewall cracking, cracking between the treads, etc. In the car tire industry, I've sold one year old Yokohama's with small cracks already in the sidewall. We have some cheap truck tires that crack pretty bad in the first six months, but you get what you pay for. The motorcycle tires show no signs of cracking, but thought I would ask the experts. Thanks.
Im no expert, but Ive read on here and RC51forums, from guys that I trust. That 5yrs is about the max age you want to run.
When I asked about running (new)GPA's on the street that were 3yrs old (on RC51forums), I beleive it was Sub, that posted a pretty good justification of why.
Once Im able to find the post I will pass that info here.
An excellent question, and one that isn't discussed very much.
I bought a low-mileage '02 2 years ago that had the original tires on it - 8 years old. I knew I should change them, but I ride only occasionally - maybe 300-500 miles a year, and the tires still looked good. I replaced them this year and the tires still look great - no cracking at all, decent tread, etc. and they are now 10 years old.
Now, I know those 10-year old tires are not as good a they were when new, but I have no idea how degraded they are... or aren't...
Point being that MC tires are built much differently than car tires and if you don't see cracks or wear bars showing or obvious cupping or chunking, then it is difficult to tell how degraded by time they are.
I think that's a bit premature for street riding. For track use maybe five years is a good guideline. Michelin will tell you five years old max for their track tires anyway.
I have two street bikes now with tires more than five years old. They still look and behave like new. Hell, I still have the original Yokohama's in a box that came on my 1976 RD400. I replaced them with BT-45's about eight years ago but they were still usable.
All DOT approved tires have a date code. It is 4 digits and describes the week and last 2 digits of the year of manufacture. So "3505" would be the 35th week of 2005.
.....1976 RD400. I replaced them with BT-45's about eight years ago but they were still usable.
To some "usable" means they can retain air in them, to others "usable" means they can corner high G numbers at the track, they are not squared off, and they flow water in the rain. If a classic bike only sees 50mi/year on a ride around the neighborhood just to keep it running and lubed, and while having the limited qualities of a dry tire in mind, then a tire can last many many years. If you push the bike to the limits on canyon roads and tracks, last year's tires may be trash.
I think that a single period limit can not be set for all tires as there are different parameters that make them deteriorate.
1 Composition: Natural/Synthetic rubber content, the first tends to deteriorate less with time than synthetic. I have heard stories that Bridgestone has larger natural rubber content than other manufacturers, but I have seen no data.
2 Sunlight/UV Exposure: This definitely helps tires to deteriorate but some manufacturers these days add more UV protection than others. I've had Metzelers that I like change colors within 5-6 months (brown). Apart from running in clear sunlight in the middle of the day it is best to keep tires and the bike in the dark.
3 Heat/cooling cycles: There seems to be a limit on how many cycles a tire can take from heating up and cooling down to where its friction characteristics begin to decline. The same batch of tires can be separated and if one runs a single 500mi run and an other 10 50mi runs, you can be sure the first (if not overheated) will be in much better condition than the second.
4 Allowed to sit loaded in a single position for long periods of time: I was told once by a chemist that rubber should be thought of as a liquid that is not very viscous but in large periods of time it will try to flow by gravity downwards. So rotating tires in different positions when they are not in use is a good idea.
Also if the load is not taken off of them and is concentrated in a spot that spot changes in quality (dry/hard) to the rest of it.
So, some of us due to habit can maintain tires longer when they are not used often than others, while others wear them out way before they get old, dry rotted, or sun cooked.
__________________ "The most violent element in society is ignorance" Red Emma Goldman
I've always made sure to lay down some cheap ridge and park my bike on them so the rubber doesn't have direct contact with the garage floor. Or I put it on stands.
To some "usable" means they can retain air in them, to others "usable" means they can corner high G numbers at the track, they are not squared off, and they flow water in the rain. If a classic bike only sees 50mi/year on a ride around the neighborhood just to keep it running and lubed, and while having the limited qualities of a dry tire in mind, then a tire can last many many years. If you push the bike to the limits on canyon roads and tracks, last year's tires may be trash.
I think that a single period limit can not be set for all tires as there are different parameters that make them deteriorate.
1 Composition: Natural/Synthetic rubber content, the first tends to deteriorate less with time than synthetic. I have heard stories that Bridgestone has larger natural rubber content than other manufacturers, but I have seen no data.
2 Sunlight/UV Exposure: This definitely helps tires to deteriorate but some manufacturers these days add more UV protection than others. I've had Metzelers that I like change colors within 5-6 months (brown). Apart from running in clear sunlight in the middle of the day it is best to keep tires and the bike in the dark.
3 Heat/cooling cycles: There seems to be a limit on how many cycles a tire can take from heating up and cooling down to where its friction characteristics begin to decline. The same batch of tires can be separated and if one runs a single 500mi run and an other 10 50mi runs, you can be sure the first (if not overheated) will be in much better condition than the second.
4 Allowed to sit loaded in a single position for long periods of time: I was told once by a chemist that rubber should be thought of as a liquid that is not very viscous but in large periods of time it will try to flow by gravity downwards. So rotating tires in different positions when they are not in use is a good idea.
Also if the load is not taken off of them and is concentrated in a spot that spot changes in quality (dry/hard) to the rest of it.
So, some of us due to habit can maintain tires longer when they are not used often than others, while others wear them out way before they get old, dry rotted, or sun cooked.
Yes, some people wear out tires faster than others. I'll agree with that. That's quite a generalization.
Yes, some people wear out tires faster than others. I'll agree with that. That's quite a generalization.
Would you agree that you can have 2 sets of the same batch on identical bikes, the one pushed to the limit on a long track day, the other gently ridden on a mountain road for equal amount of hours and miles, and while the first set would have been overcooked/heated and it is done, the second set is still fresh? Looking at them does not reveal much of a difference.
Then you have an other 2 sets, one with a stamped date of 2012, left on a southern storefront window in AZ for 2 months that you rather buy instead of the one kept in a barn in Vermont for 2 years that I buy and we take them to the track and we both do much better laps with the old Vt tires, despite of how differently we ride.
PS If you leave tires on the same side towards the sun for long you will be cornering on the other side better than on the sunny side.
__________________ "The most violent element in society is ignorance" Red Emma Goldman
The temp/ age thing is debatable, but I figure that on a street tire, if I can still dig a thumb nail into them and they're not all blue from being overheated and having the oils cooked out, they're probably still good. A track tire is different, and I would be more concerned about temp, age, UV rays, ect.
One last thing to think about: When those tires are shipped from Japan and the UK, they're coming over on a boat, and I'm pretty sure those holds get below freezing, especially in the winter.
As far as I know one of the main reasons for tire "aging" is the fact that during a long period of time, the oxygen within pressurized air inside the tire will penetrate through the somewhat porous rubber material, reacting with the different materials that consist the tire carcass, oxidizing them. After the oxidizing process has crept through the whole tire, the characteristics of the rubber compound have changed significantly from the original.
This is the reason (or one of the reasons perhaps) why even a "brand new" (never used) tire that has been stored properly in the dark (to avoid UV deterioration) and in even temperature, will feel hard as a rock after a certain number of years when compared to a fresh tire. More information on rubber oxidization can be easily found in any article that discusses nitrogen inflation. Nitrogen is an "inert" gas (doesn't react easily with anything) which means that filling tires with it should increase tire life, in addition to other claimed benefits.
I've seen at least one "weird" crash from an experienced rider on 5-6 yrs old unused slicks for no other apparent reason than the fact that the tire characteristics were significantly deteriorated during the long storage period.
"Heat Cycles is not an issue with Dunlop racing tires as it would be with other brands."
How many heat cycles would a racing tire go through, Dunlop or other? I don't believe too many.
But I would agree that overheating a tire would be a bigger issue than heat cycling.
__________________ "The most violent element in society is ignorance" Red Emma Goldman
Age of Tires
Thanks for helping out a guy when hes down.
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