Tyre sizing issue

[ashley348]

Hi, my Whyte Hybrid commuter has 700x38 size wheels. I ordered a new rear tyre to that spec, and it's too thick to clear the frame, Michelin Protech. Any idea what's gone wrong please? Thanks

 

[ColinJ]

Hi Ashley.

There is a bit of variation between different types of tyre of the same nominal size. For instance, I have had 25s which are nearer 24 and some nearer 26. It also depends on how wide the wheel rim is. Some cause the tyres to bulge more than others.

It sounds like the combination of your new tyre and that rim don't quite work out for you. You will either have to go to a slightly smaller size of that type of tyre or get the exact type of one that you had before.

PS I did a quick search and found someone saying that he measured his Protech 38mm tyres to be nearer 42mm, which would explain your problem if it is the same for you!

 

[Cycleops]

Oh dear, sorry. Seems like they are out of spec as suggested above, and by some margin. I would of thought there was a bigger tolerance within the frame but it can’t be helped. I would return them, explain the problem and ask for the next size down, if they do them in Protech, otherwise ask for another brand. If they’re a reputable supplier they should play ball.

 

[rogerzilla]

Sometimes the size embossed on the sidewall is different to the printed label (I once had some Specialized Turbo S tyres where the label said 700 x 25 but the embossing said, and they actually were, 700 x 20).

Most of the time, it's just that manufacturers don't care. I found Marathon Plus 38mm tyres to be a lot larger than the previous 38mm tyres on SO's bike, and had to trade them for 35s.

 

[ashley348]

Gosh, how silly this is. I do wonder why the frames are so tight against the wheel TBH. I ordered them from Trendz, but their not being particularly helpful with the return, it will be at my cost for instance. So what's the size down please?

 

[SkipdiverJohn]

The easy solution would be to see if the 38mm tyre will clear the frame when fitted on the front, and if it does, then use it on the front and put the existing front tyre on the back until it wears out then next time fit a 35mm one on the back. That way you don't need to mess around returning items to the supplier.

 

[Ajax Bay]

These are 40-622. On the Tredz site, go for the 700-35c.

 

[MichaelW2]

Within one model, bigger tyre width ( eg 40mm vs 38mm) means a wider tyre.
Between brands it is generally the case. In the narrow/mid size of 28mm, all bets are off. They can range from 25 to 32 from brand to brand.

As suggested, try your new tyre on the front.
Once you have a reliable, well fitting brand of tyre, just stick with it. I use plain Schwalbe Marathon and Big Apple tyres so I always know what size to get.

 

[ashley348]

The easy solution would be to see if the 38mm tyre will clear the frame when fitted on the front, and if it does, then use it on the front and put the existing front tyre on the back until it wears out then next time fit a 35mm one on the back. That way you don't need to mess around returning items to the supplier.

Thanks, I've now done that!!!

 

[ashley348]

Hi again, my rear tyre was flat today, the valve has become separated from the tube itself, Continental, 3 months old. Could somebody advise which size I need to order please? I'd like to get a Slime self healer etc. Thanks!

 

[weareHKR]

700 x 32 -45 will suffice, just make sure you get the correct valve type!

 

[ashley348]

The guy at Halfords gave me this, clearly wrong, they're so useless!!!

 

[SkipdiverJohn]

Im not too convnced about buying slime-filled tubes. If you read up on the subject, factory-supplied slime tubes seem to have a worse reputation that using an ordinary tube then injecting tubeless tyre sealant into it yourself. Slime is often regarded as less effective and more likely to just make a mess if it does get punctured. Other sealants are better thought of than slime.

 

[SkipdiverJohn]

The guy at Halfords gave me this, clearly wrong, they're so useless!!!

The tube youve been supplied will physically fit but you will be stretching it a bit more than intended, so the rubber will be a bit thinner. it may or may not be more puncture prone. I like to use tubes on the large size so the rubber is thicker when inflated, but weight-obsessed riders do the opposite and run narrow tubes inflated larger.

 

[Ajax Bay]

The guy at Halfords gave me this, clearly wrong, they're so useless!!!

It will be fine. In fact you'll probably find them easier to fit because they're a bit undersized. I agree with Skippy: they are no more likely to puncture (and just as likely for the sealant to work).
I normally run narrower inners than my tyres would 'take': for the ease of fitting, not for weight-weenie reasons.