The fact that the lightest tyres and tubes are typically manufactured for racing and run the highest pressures tends to mask underlying principles. As more diverse high pressure tyres become available for a growing range of machines, the truism is perhaps less true. I've written down some truisms of my own that you might consider when next replacing your tyres.

I don't claim any great expertise, but would point you at some fellows with more knowledge, time and money than myself who have done some serious testing. While some of these results may be a year or two old, the trends are not. Spend a few moments of rubbery fun at:

http://www.legslarry.beerdrinkers.co.uk/tech/JL.htm

There are many myths and skewed truths to consider. Here are my biased views based on the research of others, my own narrow observations, and a little simple science.

Rolling Resistance

·         Given the same tyre construction, width, pressure and rim shape, a bigger diameter wheel has less rolling resistance than a smaller wheel.

·         Given the same tyre and pressure, a lighter load has less rolling resistance than a heavier load.

·         Given the same tyre construction and pressure, a wider tyre rolls better than a skinnier tyre.

·         Given the same tyre construction and pressure, a wider tyre has a shorter contact area on the road than a skinnier tyre.

·         The more supple the tyre construction, the lower the rolling resistance

·         The smoother the road surface, the less effect wheel diameter plays.

·         The rougher the road surface, the more benefit from subtle, well-damped suspension or from wider tyres.

·         Given the same tyre, a heavier tube increases rolling resistance.

·         Just because a manufacturer says a tyre is fast doesn't make it fast. The older Vredestein Monte Carlo 20 x 1.3 tyre with obvious tread pattern is not only typically cheaper to buy than the new Vredestein S-Lick 20 x 1.3 with modern round smooth finish, but is a far superior rolling tyre. Only tesintg and experience can determine those sorts of differences.

Wind Resistance

·         Given the same tyre width, a smaller diameter wheel has less wind resistance than a bigger diameter wheel.

·         Given the same tyre diameter, a wider tyre has more wind resistance than a skinnier tyre. 

·         The front wheel of the bike produces the biggest wind resistance.

Rolling Inertia

·         Given the same tyre construction and width, smaller diameter tyres are lighter.

·         Given the same diameter and tyre construction, wider tyres are heavier.

Puncture Resistance

·         Puncture resistance and performance are at opposite ends of the tyre world. Choose what's most important for your use. The superlight tyre that your 50kg riding mate uses with great durability and success is possibly not going to offer the same durability and success if you weigh 100kg.

·         The best rolling tyre, with the lightest tube likely offers the least puncture resistance.

·         The worst rolling tyre fitted with a solid tube rolls like a dog but never punctures. Good choice for that training/commuting ride :-) I've never used them but here are some links:

http://www.greentyre.co.uk/

http://www.stopaflat.com

·         The fastest time between two points should not be measured by the number of punctures you fix.

·         Getting the last few kms out of that very fast, very expensive tyre will seem like very poor judgement if it explodes at the wrong time.

Comfort

• Given the same tyre construction and pressure, a wider tyre is more comfortable than a skinnier tyre.
• Lower pressures provide more comfort. If you want to run lower pressures with least loss of rolling resistance, consider wider tyres.