Is visual inspection sufficient for assessing if old tyres are still good with respect to rubber degradation (i.e. not cuts/wear)?
I’ve come across some things that suggest 5 years is pushing it and digging through some receipts, all my tyres are ~8 years old. However, they all seem fine (and I’ve ridden on them 6+ months ago) and I can’t really find much from manufacturers websites. No date codes on the tyres or packaging themselves (which I’d expect if there was a hard limit).
Perhaps I should send some emails to manufacturers.
Not riding at the moment but thinking about getting at least one bike ready.
People pull bikes out of their garages and ride on tires that are 20 years old all the time. If they pass a visual inspection, and mount without any issue. They are going to be fine to ride. They may not last as long as a new tire, but very unlikely to completely fail at a moments notice.
A lot of mine feel less grippy when they get older, but chucking them out would be an environmental sin. I don’t think the casings are unsafe. For these reasons (and the dramatic improvements in tyre performance over the last 10 years) I don’t stockpile tyres any more.
I wouldn’t trust tires more than 5 years old. We literally entrust life and limb to 220 grams of rubber. There really isn’t much margin for error and 8 year old tires are probably okay but probably isn’t good enough considering the risks.
It’s worth keeping in mind that as tires age, they lose oils and dry out. That coupled with the tires hardening means there will be less grip. The tires could also be more susceptible to chunks of tread coming off or other damage.
IMHO, the loss of grip is the bigger issue for riders, especially in cooler temps, rain, etc. Sliding across an asphalt skin grater is never fun.
I’d spring for new tires, if it were my choice. Not all tires are expensive.
Plasticisers, rather than oils, at least for nitrile rubbers.
I don’t think that’s the primary degradation mechanism for the rubbers used in bicycle tyres; they are prone to oxidative degradation which shortens and cross links the polymer chains, reducing elasticity and increasing hardness. One of the things you can do to preserve rubber is to store it in an anaerobic environment (eg a sealed metal or glass container with oxygen absorbers, prepper style).