tires for my mountain bike

Question
QUESTION: Hello,

I have a 19 year old mountain bike which I use for commuting to work. I think the tires need replacing and I am wondering whether I can get narrower tires. Currently the tires on it are 1.75 inch. The rims say 26 x 2.125. What range of sizes would fit? How do I know whether the tires are compatible? What would you recommend for commuting (45 minutes each way) and recreational riding (up to 2 hours)?

Thank you.

ANSWER: Well, there are a number of questions wrapped up here.  To answer the question about rims, you can fit most 26 inch mtb tires on the rims.  I think the 2.125 reference is probably to the fact that the biggest tires you could fit on a 26 inch rim 19 years ago were 2 1/8 inches in diameter.  There are plenty of bigger ones now, however, their width might not fit between your chainstays and seatstays (the thinner frame tubes in the back that comprise the rear triangle behind the seat).

If the recreational riding is on smooth or asphalt trails, you can most likely go with a slick (treadless) tire that will also be great for your commute.  In a 26 inch tire (for a 26 inch rim), slicks can get pretty narrow, but really shouldn't go below an inch because of the width of the rim.  A tire too small will not be able to seat tight against the rim walls and will allow the tube to sneak out the side.  Really, most any 26 inch slicks will be fine, such as the Specialized Nimbus, Maxxis Detonator, Ritchey Tom Slick, Tioga City Slicker or IRC Metro Slick tire.  The more slots and grooves, the better the wet weather traction.

If the recreational riding is on some loose dirt or gravel, a semi-slick may make the most sense.  It will give you some noise on pavement, but will grip better on dirt.  A semi-slick has a very minimal tread in the center and knobs on the side for when you lean the bike in a corner on loose stuff.  Possible tires might be Ritchey Speedmax, Maxxis High Roller, Kenda Kwicker, or Geax Mezcal.

To sum up, you have at least two styles that are ideally suited for what you described: Slicks and semi-slicks.  The tire size will be 26 inch by 1 inch or more, up to a size of 2 and 1/8 inch.  Ideal would probably be 26 X 1 1/2 inches, depending on your desire for shock absorption (the bigger, the softer).

I hope this answers your question,

Graeme

---------- FOLLOW-UP ----------

QUESTION: Hello again,

Thanks for your advice!

Since I am only riding on paved surfaces, ordered 26 x 1.4 Ritchey Tom Slick tires. I also ordered some new inner tubes (26 x 1.25-1.5). I have taken off the front wheel and put on the new tire and tube. I inflated it, but it is still really loose. It doesn't go to the edge of the rims at all. Did I do something wrong, or this mean I have the wrong size after all?

Thank you!


Answer
Okay, let's figure this out.  It sounds like you have an older rim that may be quite wide.  Can you measure the outside between the walls of the rim?  If it is 25mm/1 inch, you may indeed have trouble getting the "bead" (the hardened lip on the inside circumference of a tire) to "seat" against and under the lip of the rim.  If you inflate to the recommended inflation located on the side of the tire and the beads do not seat against the rim, you are right, you have the wrong size.  Assuming you have one of the wider rims (23mm or wider) you would be better off with a 2 inch slick tire.  I just went downstairs myself and looked at my slick wheels.  They have Tioga City Slicker 1.95 inch tires mounted on 17mm (2/3 inch) wide rims.
I am not sure where you got the tires, but you should be able to take/send them back for an exchange to a larger size without a problem.
My apologies for not getting a better feel for the size of your rims, but those biggies are pretty rare, so I thought it unlikely.

Just to cover all bases, the rims and tires both say 26", right?  I have accidentally purchased a 26" tube for a 24" rim before. . .

In terms of looking on the bright side, be happy - a larger diameter tire will give you a much smoother ride on the paved surfaces you will be on.

Graeme