Originally Posted by
Cambronne
It depends upon what type of tires you use,whether they are fast wearing racing compound, or tougher touring tires, your weight, and the tarmac surfaces upon which you ride. A rough (very rough) rule would be: See to your racing tires after 1 000 miles of road riding, (or a weekend's racing) and your touring tires after anywhere from 2 500 to 4 000 miles.
Some brands outlast others... Michelins will go on seemingly forever, although you may wish for their demise, as their grip is inferior to most other brands. Continentals, in my experience, grip better, but last half as long.
Examine the tires for signs of wear... Road tires that have ribs or tread patterns will wear smooth down the centre, Slick road tires will wear "flat" across the centre. Also, look for cracks, tears, small chunks missing on the tread surface. These are all signs of worn out bicycle tires.
If you detect wear on the rear tire, but the front looks okay, as is nearly always the case, you can dismount the tires and swap them, and run the better ex-front tire on the back.
Always save the best of your old tires. A worn spare is better than no spare.
Replace tires with ones of the same width, and, if you liked the originals, the same brand. You can experiment with slightly narrower or wider tires, but be advised... a few mm of width will noticeably change the bike's handling.
I just ordered another set of Performance GT2 Kevlar, in 700x25 size, for US$16ea. See them at
http://www.PerformanceBike.com. This makes perhaps five sets of these that I've used, and I average about 4 000 miles per set, rotating them once. The kevlar belt provides that little something extra against punctures. They are heavier than more expensive tires, and the herringbone tread means that they're not as fast as racing slicks, but they're exceptionally good at keeping air within and glass shards, nails, and road debris without, and that's what counts for me.
One can buy a perfectly suitable pair of tires for under or around US$50. See what your LBS has on offer.
Now, if you go roadracing, that's another matter... budget for $100 worth of tires (that's for two) every 1 000 miles or less. Or, ride for a tire manufacturer!
I tried Michelin Krylion and Conti gatorskins. Although these tires are aimed at different types of riding, the gatorskin, as expacted, is harder wearing, less grippy.
I didn't think it was good idea to swap front and rear tires. It's better to have more grip on the rear tire to stop oversteer, it's better to understeer which will force you to slow down in the corners (until you get two nice new grippy tires).
Perhaps worn spare is better than no spare, but I'd say it's the other way round. If you have to replace your tire in an emergency (ie. you just HAVE to go out for a ride), then you're much more likely to get a puncture in the newly installed *worn* tire. If you had *no* tire, then you wouldn't go out for a ride, and have zero chance of a flat.
I was using Krylions for training but these days I'm commuting and I found Gatorskins are superior choice. In fact, when I go back to training, I might just stick with gatorskins. The Krylion were a real beautiful tire, I didn't get too many puncture and the grip was good. The Gaotrskin gives me no grip in comparison, a harsher ride, but they hardly puncture, and that gives me more training time. Actually I should say "work out" time since training might imply I'm training for a race (which I'm not) in which case you need a good cornering tire to practice your cornering skills.