Walter S

I've never been very scientific about this. I used to ride road bikes with skinny tires. I would start getting a flat spot in the middle of the tire and over time got to know when they were getting thin enough that I'm asking for a flat. Now I ride my Surly with much bigger tires. Currently Continental Travel Contact 26x1.75. I've got well over 10k miles on them and I look at them and they seem fine. Lots of rubber on the contact patch and (naturally) the rest of the tire.

I fix flats matter of factly when they happen. But I'd much rather avoid learning the hard way, when it was time to replace my tire.

What should I be looking at?

sstorkel

Many tires have "wear indicators": dots or lines on the tire that are lower than the surrounding rubber. When they disappear, you know the rubber I had worn thin enough that it's time to replace the tire.

mdilthey

Check the sidewalls for wear. That's where my Schwalbe's went. Took like 6,000 miles (Supreme Plus), but that's where.

bikenh

Funny thing is you can still run trouble. On my trip this summer I started getting flats quite regularly. I flat out took everything off, including the rim tape and started searching for the reason and couldn't find and reason. Tread wasn't showing, nothing was poking through the tire, etc. I still kept getting flats quite regularly(sometimes I would only ride around 100 miles between flat tires). I finally replaced the tire and stopped having troubles. In the past, two years ago I had the same thing happen on my first trip and it was the rim, a small chunk of the rim flaked off and got caught up underneath the rim tape and kept giving me flats. No luck with that this time though. Still don't know what was wrong with that darn tire.

Lou Skannon

When you go touring with a heavy load on the rear and a light load on the front; its interesting to compare the appearance of the tyre. The tread depth maybe the same but the rear will look different. I think this is due to the pulverising done by uneven surfaces with the extra weight. Some years ago; I did the Otago Rail Trail in New Zealand, fully freighted, and ruined a new tyre in a short time on the rough surface. I had constant punctures until I replaced it.

SparkyGA

I just guess.

At home I'll run tires till there getting flats and nearly bald, but on tour I'll replace them when I figure I'm at about 75% worn out (totally just a guess) and hitting the next city that I can get new tires. I feel bad tossing a tire with some decent life left, but rather not be stranded in a 3rd world country from a situation that could be totally preventable by not being a tightwad...

bradtx

Walter S, I SWAG the tire's condition more often than not. I did recently replace some Panaracer Crosstowns with good tread because they were becoming hard, which made cornering a whole separate adventure. The upside was that they wore like iron. I hadn't had the tires quite three years and I guess they were on a retailer's shelf for a long time.

Brad

staehpj1

While on tour I run them until cord is showing on the rear tire or until it starts to flat frequently, which ever comes first. I usually change the front before it is completely worn out when changing the back one, but do not do so with every rear tire change. I probably change the front tire with every other rear tire change. Oh and I do not generally bother rotating front to back.

I used to start tours with a fresh set, but as I started touring more I quit that practice. Some folks save the half worn tires to run them later at home, but I never wound up putting them back on. and decided that I'd rather not waste all that wear on expensive tires. I figure installing new tires in the middle of a long tour is no big deal, so I change them only when worn out rather than at the start of every long tour.

andrewclaus

For the things that normally give me a flat, like goathead thorns and those tiny pieces of wire from radial tires, that extra millimeter of rubber on a road tire won't stop them. Rubber serves one function on a tire--traction. It has little intrinsic strength or puncture resistance. So I wait, if I can, until the fabric is showing. (But I'm living on a strict budget and I'm afraid it shows.)

staehpj1

Yeah goat heads and radial tire wires work their way through no matter how much rubber is left. That said, I have found that sometimes near the end of their life tires start to pick up sharp bits of stone or glass and get flats.

fietsbob

Schwalbe green guard and the similar band on the Marathon plus is another color than black. its out side the casing , under the tread rubber.

Nycycle

When my back tire started going flat just after thinking about a goat head,,,I changed it.