In bicycle tyres the tread is far less important than for instance in car tyres. So using a tyre with a worn out tread is less of a problem that is of course with the exception of MTB tyres.
When the puncture protection belt or the carcass threads can be seen through the tread the tyre has reached its wear limit and must be replaced. As puncture resistance also depends on the thickness of the tread layer, it may be useful to replace the tyre sooner.
The sidewalls of tyres often fail before the tread is worn out. In most cases, this premature wear is due to prolonged use of the tyre with insufficient pressure. Checking and re-pumping the inflation pressure at least once a month with a pressure gauge is most important.
It is difficult to answer this question, as mileage is influenced greatly by tyre pressure, load, road surface, temperature and the rider. For example, when used in hot weather with a heavy load and on rough asphalt, a tyre wears much faster.
As a general guide, you can expect a tyre mileage of 2000 to 5000 km from Schwalbe standard tyres. The tyres of the Marathon family usually last between 6000 and 12000 km. With the light Marathon Racer and Marathon Supreme, the performance is a little lower (approx. 5000 to 9000 km). The Marathon Plus is outstanding with its extremely high mileage of often much more than 10000 km.
No useful mileage data is possible for MTB tyres, because the influence of riding style is too dominant. Our racing bike tyre Schwalbe One lasts from 3000 to 7000 km.
Unfortunately, many tyres do not reach the possible mileage because they are continually ridden at inflation pressures that are too low. Insufficient inflation pressure means the tyre cannot bear heavy loads. The tyre sides have to deform excessively when running. The tyre can only stand this kind of treatment for a limited time. At a certain point there is too much load on the sidewall and it tears.
Fig. 1 shows the typical fatigue cracks which arise from low inflation pressure. A few large cracks in the upper area of the sidewall. In comparison the second figure shows normal aging cracks (due to old age and/or poor rubber compound).
These cracks are rather small and distributed evenly across the whole sidewall. In practice the transition between these two crack types is often seamless so that the cause is not always clearly visible.
Figures 3 to 5 also show clear symptoms of continued riding with insufficient inflation pressure. Typical abrasion marks: The tyre is not bald in the center but on the left and right sides. Typical walk traces in the tyre and on the tube.
Our tyres are usually designed for bicycles and therefore not always suitable for multi-track vehicles, such as tricycles.
Unlike a (single-track) bicycle, a tricycle usually will not tilt in a curve. In a curve the vehicle then “pushes” transverse to the direction of travel via the steered front wheels (understeering). Depending on the riding style and the vehicle design this effect can result in a significantly increased wear.
An extremely increased wear, e.g. when the tyres are worn down after less than 1000 km already, can be the indication for an improperly adjusted tracking of the vehicle. Even when riding straight ahead the tyres which are standing transverse to the direction of travel generate increased friction and thus excessive wear.
The same also applies to trailer tyres. Usually, the tyres of a bicycle trailer must neither transfer driving nor steering forces. That’s why these tyres show clearly less abrasion than bicycle tyres. If these tyres are affected by remarkably heavy wear, this has most probably to do with the tracking adjustment of the trailer.
Schwalbe tyres can be stored for up to 5 years without a problem. If possible, they should be stored in a cool, dry and, most importantly, a dark place. When stored properly, even longer storage times may be possible..
If fitted on a rim, tyres should always be inflated or the bicycle should be hung up for storage. A bicycle left on flat tyres for an extended period of time may damage the sidewalls of the tyre.