Not all 29x2.25 tyres are equal

[ChristoErasmus]

Recently I decided to try a different brand of tyre - just because... they were marked 29x2.25 (ETRTO 57-622) and hours of reading reviews I gave it a go.

I mounted these tyres on a 25mm ID rim which is 2mm wider than the rim used by the manufacturer's reference measurements.  The tyres were no where near the expected width of 2.25 inch or 57mm, they measured 53mm which is the width of a 2.1 tyre.  Don't get me wrong, 4mm is not a lot but visually on a tyre you will be amazed at the difference in volume and appearance.

I started measuring the new tyre after taking it off the rim and found that the width from bead to bead was 138mm compared to the 150mm of all the other 2.25 tyres (ETRTO 57-622) I could get my hands on.  Taking the formula for the circumference of a circle (c = 2*pi*r) and adding the width of the rim to the width of the tyre it was clear that the 12mm difference was the reason for the loss of width and volume.

This story is to make you aware of the fact that regardless of the numbers printed in the rubber you still may end up with a tyre that is not what you expected.  When trying a different tyre, measure the width from bead to bead (across the tread) before buying.

[MORNE]

was it a maxxis lol. they are the worst at this. But it is well documented. Yes different brands tyres run at different sizes. I have a Pirelli road tyre that says 25mm on the sidewall but measures 28mm and a goodyear 25c one that measures 24mm. Maxxis mtb tires always run small imo. other brands like Scwalbe and conti ten to run either spot on or even slightly bigger. especially if you leave them inflated at max PSI overnight

[Spafsack]

Same with my wifes tyres versus mine, hers are marked as 2.1 but are the same width as my maxis 2.2's, hers are vitoria. Not a massive game changer, just interesting to see. 

[RocknRolla]

so after all the math. can you feel the difference on the trail, or is this a visual thing?

[Thermophage]

You, unfortunately, cannot take the 2.25 measurement as the tyre width. On the sidewall of the tyre should be embossed the actual width (in mm) and that should compare well to your caliper measurement.

Don't ask me why they don't speak to one another. I've heard stories that thet printed width has to do with the height of the tyre, but haven't investigated that yet.

Here's an example of my old 275x2.5 Maxass DHF DD MaxTera. In this case the 63mm corresponds well to the 2.5" stated width. But don't expext it to always be.

As okes said prev...Maxass stated width and measured don't like to speak to another.

[MORNE]

58 minutes ago, RocknRolla said:

so after all the math. can you feel the difference on the trail, or is this a visual thing?

 

[fanievb]

 

[Jakkals.]

2 hours ago, MORNE said:

 

Jen pre-op.

[love2fly]

Sooo you made me go measure my Ardent Race 2,35. Surprised to find it is almost exactly 59,something mm

[ChrisF]

2 hours ago, fanievb said:

 

EXCELLENT video.

 

Thanks

[Me rida my bicycle]

I see a lot of "hate" towards Maxxis size. Let me ask do you inflate them to maximum and leave them overnight?

I do this with all my Maxxis as they say you should and have never had a undersized tyre, some of them come out to more even. 

[MORNE]

2 hours ago, Me rida my bicycle said:

I see a lot of "hate" towards Maxxis size. Let me ask do you inflate them to maximum and leave them overnight?

I do this with all my Maxxis as they say you should and have never had a undersized tyre, some of them come out to more even. 

The newer ones are better apparently. but maxxis are basically an internet meme under mtb’ers for running small lol. I had a set of minion dhf 2.5’s that meadured smaller than 2.35 schwalbes. A 2.6 schwalbe dwarves a 2.5 maxxis. 
 

ps: that said, i still use maxxis, i just dont use them when i want something for it’s volume. That reminds me, honorable mention to continental Trail King 2.4’s ( the old Rubber Queen) are actually closer to a true 2.5.

Edited May 14, 2021 by MORNE