Before you buy bike tires

Last week About.com posted an article by David Fiedler about buying bicycle tires. While it has some good advise, there are a few things that are plain wrong. I am surprised that someone who claims to be an expert with hundreds of articles and two books would publish an article like this without even checking his facts first.

So you don’t have to click on the article and read it yourselves I will summarize and correct the sections that need fixing.

Know What Size Tire You Need – Dimensions

1. Most adult MTB, hybrids etc use 26" tires – OK
2. Most BMX bikes use 20" tires – OK
3. Most road bikes use 650mm or 700mm tires – Wrong!

Rims practically all over the world are measured as a diameter of the bead seat, tires are measured the same way, from automobiles to motorcycles to bikes. Road wheels in modern bicycles come in 650C (becoming more rare except in the smallest adult bicycles) or 700C. These designations are from a french system of measurement. Although 700C is supposed to imply a nominal diameter of 700mm that is not how the tire is measured or labeled. A tire for a 700C rims is usually labeled 622-xx, where 622 indicated the diameter of the bead seat 622mm and the xx is the nominal tire width, 23mm for example.

Tread Type

1. MTB tread is useful – OK
2. Road bike with smooth tread is ok, he implies a little tread will help hold the road better – Not entirely correct.

While different tread patterns on tires used in off road riding can actually contribute to traction and safety. Tread on a bicycle road tire serves no useful purpose. It is simply a marketing gimmick. Tire compound plays a much more important role in adhesion than any miniscule ridges that might exist in the inch wide patch of rubber on the road. We are used to seeing tread on a tire and have come to expect it, so tire manufacturers give us tread. If you really need the tire to grip the road better, lower your tire pressure by 5 psi, or buy tires with softer rubber compounds. Never buy a road tire based on tread pattern.

Durability of the Tire

1. Spend a few dollars more on a quality tire – OK
2. Kevlar belts under the tread for more puncture resistance – OK

I would also add that staying away from ultralight tubes might be a good think if your number one criteria is puncture resistance. There are also many good reports, especially in the MTB world about using some sort of tire sealant. To be honest I use tire sealant in my own tubular tires and in 4000 miles I have only had one flat that the sealant didn’t fix and it was a cut to the sidewall of the tire. I am a big believer in sealant. Now, in tube tires I do not recommend sealant, a personal choice, tubes are cheap and easily replaced. Sealant all over the inside of a tire is messy and must be cleaned out before mounting a new tube. I feel even more strongly against any tube that has Slime inside it.

Weight of the Tire

1. Weight is not important – OK

Only time it might matter is on a track where very high pressure light weight tires are used. On the road err on the side of caution.

What Width Do You Want?

1. Skinny = Fast – What are your saying?
2. Skinny needs more air pressure – OK
3. Skinny means harsher ride – Not always
4. Wider tires will make you feel more steady – Uh, not really

Skinny or wide will depend more on your riding style, road conditions and weight and will have only a minimal effect on whether or not you can go faster on one tire over another. There is also a point of diminishing returns when it comes to skinnier = faster. You can have a tire that is too skinny. This leads to the second point. In order to support the same weight rider a tire has to have a similar volume of air. The skinnier the tire is the more pressure necessary to provide that volume. The big side effect of this increase in pressure is that a firmer tire actually makes you slower. A tire that cannot conform to the irregularities of the road provides less traction and less traction means less speed. So all you guys out there that insist you are faster because you pump your tires up to 140 psi, guess what, you aren’t! Ride harshness is a combination of factors. In most cases using a 23mm tire as opposed to a 25mm tires you will not be able to tell any difference in ride harshness, especially if you ride with appropriate tire pressure for your weight not just the maximum allowed. Tires as wide as you can fit between the brake calipers are good for people carrying heavy loads, or the ultimate in a soft ride. Sometimes that is a good thing. But does it really make you more steady?

Determining Your Tire Size

1. Dig out the manual or paperwork for your bike if you have it
2. Go to the manufacturer’s website, which usually has specs for all of its bikes.
3. Measure the rims yourself. Go rim-to-rim for the complete size, or else axle to rim, then double it.
4. Easiest of all, show it to the pros at your local bike shop. They’ll know just by looking at it. They’ll also be able to recommend the best width for your type of riding and for your specific bike.

Ok I can’t really argue with any of this, it is good advice. Of course all this only really relates to tires that use clincher construction, tubulars are a different story, but not for today