All Maintenance Tasks · Monthly
Inspect Tires for Wear and Cuts
A tire is the only thing between the bike and the road, and it fails in two ways: slowly, as the tread wears flat and the casing thins, and suddenly, when a cut lets the tube push through. The slow failure is easy to see once a month. The sudden one is usually the slow one that nobody looked at.
Interval
Monthly
Once a month, or after roughly 200 miles
Time on the job
10 minutes
Once you have done it a few times.
You or a shop
Anyone
The stop signs further down are the real answer.
Applies toRoadMTBHybridE-bikeKids
How often, really
Monthly for a bike in regular use, and immediately after any ride where you felt a hard impact or heard something hit the tire. Rear tires wear roughly twice as fast as fronts because most of the weight and all of the drive sits there. Riding through glass, construction debris or gravel shoulders shortens the interval to weekly.
The interval on this page is Monthly. Once a month, or after roughly 200 miles.
What you need
- A small pick or a blunt knife for embedded debris
- Good light
- A pump to reinflate afterward
Doing the job
Deflate a little and turn the wheel slowly
Let some pressure out so the tire is soft enough to flex under your thumbs, then turn the wheel a hand-width at a time and look at the whole circumference. Rushing this is how you miss the one cut that matters. Do the tread, then both sidewalls, then the bead where the tire meets the rim.
Read the tread wear
Many tires have small round wear indicator dimples molded into the center of the tread; when they are gone, the tire is done. Tires without indicators tell you the same thing by shape: a road tire whose round profile has flattened into a square strip down the middle, or a knobby tire whose center knobs have gone rounded and short, is worn out.
Pick out what is embedded
Run a thumb lightly over the tread and look for glass fragments, flints, wire and thorns sitting in the rubber. Lever each one out with a small pick or a knife tip. A piece of glass that has not reached the tube yet will get there over the next few hundred rotations.
Judge the cuts by depth, not by length
A shallow nick in the rubber that does not reach the fabric underneath is cosmetic. A cut where you can see the woven casing threads means the tire has lost the layer that holds pressure, and it belongs in the bin. Any cut where the casing is visibly frayed or where the tire bulges under pressure is finished.
Check the sidewalls and the bead separately
Sidewalls are the thinnest part of the tire and fail without warning. Look for cracking, a network of fine lines from age and sun, scuffs from a curb, or a section that has been worn by a rubbing brake pad or fender. Then check the bead is seated evenly all the way around: the molding line on the tire should sit at a constant distance from the rim.
Look for the shapes that mean stop
A bulge or blister is the casing already failing under the rubber. A flat spot worn through from a locked-up skid is thinner than everything around it. Either one means the tire comes off now rather than at the end of the month.
Stop and take it to a shop
If any of this shows up while you work on inspect tires for wear and cuts, put the bike down and let a mechanic look at it. None of these are things to ride out and see how it goes.
- A bulge, blister or lump anywhere in the tire when it is inflated. The casing has given way underneath and the tire can blow out. Replace it before riding.
- A cut deep enough to show the casing threads, or any hole in the sidewall. A tire boot gets you home in an emergency and is not a repair.
- Tread worn to the wear indicators, worn flat across the center, or worn through to a different colored layer underneath.
- A tire that comes off the rim, will not seat evenly, or blows off during inflation. Stop and have the tire and rim compatibility checked rather than trying again with more pressure.
Where this usually goes wrong
- Checking the front tire, which looks fine, and using it to judge the rear, which wears at roughly twice the rate.
- Patching a tube repeatedly without ever finding the piece of glass still sitting in the tire, which then punctures the new tube in the same place.
- Storing a bike outdoors in sun for years and judging the tires by tread depth alone, when the sidewalls have aged into a network of cracks.