Buying new MTB road tyres. What size tyres are good for the rim? Kevlar?

Good advice on the continental tires from Falkovitz. There are a number of high quality, low rolling resistance 26" tires on the market though. Continental is one of the best, but hutchison and michelin also make exceptional products. With a 16mm rim you can easily go as low as a 20 mm tire, but depending on your size and the conditions of the road, you might want to stick with a 25.

On your bike the weight of the tire won't make all that much difference, unless they weigh like 700 grams. It has to do more with the inflation rating. Higher inflation means less rolling resistance, and the weight won't be much of a factor unless you're going up alot of hills.

Nope, it's not really the kevlar that does the trick, but the industry in asia would like you to think so... Ofcourse it helps, but the single most important factor for preventing flats is a good quality rubber. Quite often the manufacturer lowers the quality of the rubber in an attempt to make the consumer pay for the kevlar, and the consumer is left with a lower quality product all in all. Buy Continental's "Town & country" tires or Bontrager's "Satellite Plus" tires. Both tires have a sturdy longlasting quality of rubber, and are exellent for road use. The Bontrager is cheaper and usually more accessible, but the Continental is absolutely awesome. I've ridden them both for extended periods of time.