Can some one please explain mtb tyres sizes to me??

CUBEical

hi there i have recently got into mountain biking for the first time as an adult now i am currently re doing a bike up , and i am trying to decide on what tyres to get , the size on there at the moment are 26 x 2.4 now i thought all the tyres that go on that wheel need to be 2.4 but i am starting to learn i am wrong is 2.4 the size of the top bit of the tread ? not the bit that goes on the rims , are the rims for mtb all the same width if some one can explain all this to me that would be great thanks

Horton

Have you had a look at Sheldon Brown's site? More info than you need, but it's all there.

In answer to your question, no, not all rims are the same width - they vary depending on intended use I.e. DH rims are wider than XC rims. If on the off chance by width you meant diameter, that's a no too - currently we have 26", 27.5"(650b), and 29". 26" is the common standard for now.

2.4 is the width of the tyre but every manufacturer is different, so a 2.2 might be "bigger" than someone else's 2.3 when actually on the rim. The width of the rim also comes into it but if you're new to this, I suggest maybe just go out and ride the bike and see how you get on. Wider tyres generally offer a bit more grip but are usually heavier and slower rolling than a thinner tyre - again that is very general!

CUBEical

i have been linked the size guide on another post just now. i knew the diameter changed . and my wheels are 26. the tyres on there are xkings 2.4 and they do look massive. i just thought the 2.4 was the size of the rim that meets the tyres so i thought i could only replace them with another 2.4 witch i now have learned are a bit oversized for my rims. as its recommended that its between 1.0 and 2.3 on that size chart. im trying to find a good cheap tyre for 70% road use and 30% xc use ? did not know if it worth keeping the xkings (one needs replacing and getting some road tyres or getting a set that meet in the middle

bartimaeus

Yep, the 26" bit is a diameter - and it's not even the diameter of the wheel - it's the nominal diameter of the wheel+tyre, but that assumes a 'standard' tyre. You will now also see lots of 29ers (29" nominal diameter) and now 650b (nominally 27" or 27.5" - they are still arguing about that).

The wheels themselves will have a marked rim diameter... so your 26" wheels will say 559 (this is now an ISO number in mm!) while 29ers are 622 and a 650b is 571.

The 2.4" is the width of the tyre at the tread... and here the measurement is not exactly standard so some manufacturers 2.35" may be bigger than a 2.4" from someone else. As a rough guide, 2.1" is a pretty standard cross-country width, while 2.25" or 2.35" is a wider tyre often favoured for more 'all mountain' use, while 2.4" and bigger are often for 'downhill'. For road use, and for winter mud where you don't want the tyre to float you might go narrower to 1.8" or even 1.5".

What width you use depends on what type of tyre you want, but also on your rims. Rim widths vary... my rims are fine with up to 2.25" but some wider tyres start to get a more balloon shaped profile and feel squirmy as they roll from side to side unless at high pressure. 'All mountain' and 'downhill' bikes will have wider rims to give a better profile when using bigger tyres - and to make the rims stronger.

CUBEical

Bartimaeus wrote:

Yep, the 26" bit is a diameter - and it's not even the diameter of the wheel - it's the nominal diameter of the wheel+tyre, but that assumes a 'standard' tyre. You will now also see lots of 29ers (29" nominal diameter) and now 650b (nominally 27" or 27.5" - they are still arguing about that).

The wheels themselves will have a marked rim diameter... so your 26" wheels will say 559 (this is now an ISO number in mm!) while 29ers are 622 and a 650b is 571.

The 2.4" is the width of the tyre at the tread... and here the measurement is not exactly standard so some manufacturers 2.35" may be bigger than a 2.4" from someone else. As a rough guide, 2.1" is a pretty standard cross-country width, while 2.25" or 2.35" is a wider tyre often favoured for more 'all mountain' use, while 2.4" and bigger are often for 'downhill'. For road use, and for winter mud where you don't want the tyre to float you might go narrower to 1.8" or even 1.5".

What width you use depends on what type of tyre you want, but also on your rims. Rim widths vary... my rims are fine with up to 2.25" but some wider tyres start to get a more balloon shaped profile and feel squirmy as they roll from side to side unless at high pressure. 'All mountain' and 'downhill' bikes will have wider rims to give a better profile when using bigger tyres - and to make the rims stronger.

cool good info . sounds i am definitely in need of new tyres i am now going out to garage to get the exact name of my rims and maybe a picture of the rim and 2.4 tyre on there at moment see your view on what the rim size is

CUBEical

right the rims are "alexrims disc zx24 double wall 559 x 19 6061h-t6"

drays

the important measurements here are 559 x 19

diameter is 559mm, which is 26 inches. the rims are 19mm wide.

any 26 inch tyre will fit. The tyres you have on (see OP) are 26 x 2.4. That is, they are 2.4 inches wide. For reference, I have 2.1 inch wide tyres on my hardtail.

bartimaeus

It should be straightforward... the tyres will have markings a bit like this. Yours will say 559 and then 26 x 2.4.

There are many many tyres out there that will fit your rims, so your biggest headache is choosing the 'right' one... and that will depend on where and how you ride, how light you want your tyres to be and how much money you want to spend. But I would always choose 'folding' over 'wired' as they will be lighter, easier to handle when fixing punctures and usually they will have better rubber compounds for better grip.

Plenty of choice at On-One, nextdaytyres and the usual online stores e.g. CRC and Wiggle

owenlars

Look at this downlad from Scwalbe, explains all about tyres and rims and which fits which.

http://www.schwalbe.co.uk/_webedit/uplo ... 20Info.pdf

The Rookie

More important than width is getting the right tyre for the riding you do and what you want from it, after that pick the best width of that tyre available on the same basis.

For example my rims are the same width as yours, in summer I ride with Michelin dry mountain 2.25's as they roll insanely fast and grip great on gravel, hard pack etc, in winter I swap to Panarcer XC Pro, 2.1", as it gets muddier I put a 1.8" out back for traction and if there is more mud than solid I got to a 1.8" Fire Mud tyre, bit draggy on harder surfaces but grips like brown stuff to a blanket in mud.

JBA

Get a pair of Kenda Small Block 8 1.9 or 2.1's and you'll be fine.
Fairly low rolling resistance for on the road and a surprising amount of grip for off road.