Photo of two bicycles

My girls have the exact same Nishiki mountain bikes. The purple one is actually a year newer but has significantly worse tread wear. Any idea why?

  • The tyres may look alike but the compound could be a totally different one, depending on the OEM provider.
    – Carel
    Commented Aug 24, 2020 at 12:11

1 Answer 1


Kid bike tyres tend to be on the cheaper-end of materials and wear quite fast. Most kids bikes end up where the rider out-grows the bike, so a long-life tyre is less important. I suspect the newer purple bike has slightly lower-grade rubber in the tyre than the older bike.

A child's bike would likely does less than a hundred miles in its entire life.

Riding on a low pressure can also accelerate wear on the tread.

Another cause for rear tyres to wear is when the rider is a little hoon and does M4D SK1DZ which wear flat spots. Do that enough and the tyre simply wears down in the middle.

However, I can still see tread blocks on both tyres - there's a complete carcass to wear through before that tyre needs replacing. Also, the more-worn tread will be smoother and more comfortable for the child to ride due to its lack of knobs. And it'll be faster/less effort required.

I see no need to replace that tyre, unless its getting a lot of punctures, or its cracking/crumbling.

  • 6
    The front tire is worn as well. Kid#2 has just told me she locks up both the front and rear wheels when she stops. She likes to make skid marks. That’s explains it. Thanks
    – Kenna94
    Commented Aug 24, 2020 at 0:27
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    @Kenna94 Sounds like you're raising a cyclist - well done!
    – Criggie
    Commented Aug 24, 2020 at 1:44
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    Isn’t the carcass/threads visible on the left tire? Which would mean it’s time for a new one. Or is it just dirt or chewing gum?
    – Michael
    Commented Aug 24, 2020 at 11:39
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    @Michael good spotting - I thought it was just dirt, but it could be the inner threads. The tread at the top of the wheel as pictured shows shadows of tread knobs. Perhaps that's one spot where a few more skid-stops have been done. If it is through the rubber, then replacement of that tyre is probably a good idea.
    – Criggie
    Commented Aug 24, 2020 at 12:46
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    That indeed appears to be the color marking they often put in tires to show that it is time to replace them. However you can still ride extensive mileage with a worn tire, I rode a year, quite regularly, on a bike that had a red stripe all around the tire. Just don't expect it to be reliable at that point, and be ready to get stranded with a flat.
    – Luuklag
    Commented Aug 25, 2020 at 14:21

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