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I used these tyres for one year/ about 5000 km.

They look fine/ok (not very worn), BUT, I got a first puncture two weeks ago. While looking at the tyre I noticed it has some cracks here and there, as I show in the pictures.

I am going to a race next week and I am wondering whether or not I should change the tyres.

Is there a reason for concern? Should I change the tyres or will that not make any difference?

crack 1 crack 2 crack 3 crack 4

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    What tyres are they? I suspect you're not racing on heavily puncture-protected tyres, in which case that cut might be a worry, but on the toughest tyres it wouldn't be – Chris H Jul 21 at 10:15
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    As someone who blew a tyre about 500m into a race, just because it would have been too much work to put a new one, I say, change them. – mustaccio Jul 22 at 1:04
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    Personally, if i were going to race, i'd be more worried about the rolling resistance of a £10 decathlon tyre than I would about those cuts. Its hard enough averaging 25mph without having to push an extra 20-30W just due to the tyres. – Andy P Jul 22 at 8:05
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    Sure - if you want to race buy a fast grippy tyre with just enough puncture resistance. Not going to be cheap, but in general a nice tyre really transforms the feel of a bike and is by far the most cost effective upgrade you can make. – Andy P Jul 22 at 10:17
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    This is a pure value judgment. How much do you care about the race versus not spending a few dollars and an hour to change them? We can't see inside your mind or your pocketbook. – J... Jul 22 at 13:19
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Those small cuts in the rubber tread are normal and you get them quickly after a few kilometers. I just regularly make sure that no objects are embedded in the tyre since they can dig deeper over time.

The important part is that the cuts don’t go through the casing threads. When the casing is cut through the tyre can fail. In your first photo it looks like this might be the case since it seems like it’s bulging outwards around the cut. Did you look at the inside of the tyre after your recent puncture? Was it smooth or did the cut go all the way through?

Do your tyres have a tread wear indicator? One or two dimples in the rubber tread marked with “TWI” on the sidewall. If they are gone it’s time to replace the tyre anyway.

Once the rubber gets thin tyres are usually more prone to punctures.

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    But for a race I'd change them and take a ride (60-100km) to wear them in. You can still put the previous ones back on after that. – Carel Jul 21 at 9:46
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    @myradio yes, that's worth asking a whole new question. – Criggie Jul 21 at 10:25
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    I dimly recall some tests that rolling resistance actually slightly increases with wear and new tyres have the lowest resistance. Using them for a few kilometers might still be a good idea to rule out an installation error (e.g. pinched/rubbing tube etc.) – Michael Jul 21 at 13:16
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    It's extremely rare, but it is possible to wind up with a defective tire. You'll probably know within a few km if you've got one. I would not race on a brand-new tire. – Adam Rice Jul 21 at 14:40
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    @AdamRice Indeed. Also, a brand-new tire is likely to be slick with a mold-release compound or agent that could drastically reduce traction. – Andrew Henle Jul 21 at 16:23
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There is a level of judgment call that goes into this question, but there are also two metrics that are most telling in making it: how round the tire looks in profile and how much tread thickness is left in the contact patch when the unmounted tire is pinched between the fingers, relative to the adjacent sections. The view you present, of the tread surface not in profile, would be enough to make the call in an extreme case, i.e. lots of deep cuts, but as you say that's not what you're up against here.

5000km on the sort of tire you want to be racing on in the first place is pretty considerable, although that depends on what tire it is and rider weight/power.

I think the tire in the picture probably still has some life in it were the purpose to economize, but if the race is at all important to you, go in with a fresh one. As others have indicated, some kind of shakedown ride is good, but I wouldn't split hairs about the exact amount of break-in. (At high levels it probably is reasonable to worry about that and all other aspects of tire conditioning, but for most people it's basically go on 1-2 rides.)

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