Choosing good slick tires for a MTB

Generally, when you reduce tire width AND increase pressure you get lower rolling resistance. You will also find that the steering is a bit more "lively", especially at lower speeds. (Reduce tire width and don't increase pressure and you get more flats.) As a first-order approximation, rolling resistance is proportional to the size of the "spot" your tire makes on the road, which in turn is a function mostly of weight and pressure.

You really don't need or want slicks for road riding, but a tread with relatively fine grooves. Most such tires will be perfectly smooth across the very ridge of the tire(1/4 to 1/2" wide), but will have tread on both sides, so that you roll smoothly but get the effects of the tread as soon as you tilt to one side or the other.

If you are road racing then yes, get the skinniest, lightest tyres you can find. However, if you are riding in traffic to get to work and back then you need a bit of comfort, some puncture proofing and good wear characteristics.

I have had a few Continental tyres in my time but I cannot vouch for all of them. What I do know is that they are guaranteed - get a puncture in the first year and get your money back. I was sold on that, but, when you are fixing punctures in the cold and wet on a night when you wish you were home, that guarantee really pisses you off - the puncture proof promise is a marketing gimmick that is meaningless after you have done six months on them.

Nowadays I prefer a bit of cushion with my tyres, from more volume and not from lower pressure. High pressure, relatively high volume tyres work best for me. I am also not adverse to running different widths front and rear, with a bit more cushion at the back.

I also like the reflective sidewalls although these get covered with dirt quickly if running 'V' brakes.

Having never had a flat tyre with Schwalbe Marathon or Marathon Plus tyres I would recommend that you pay the extra and give them a go. 700 x 35 is ample cushion and the extra weight of them compared to a road racer's tyre will not be noticeable since you come from having really heavy tyres. They also have enough tread to not slip like slicks if you do go off road and have to go up a wet grassy bank. I advise that you Google reviews of them, here are the available widths here:

http://www.schwalbe.co.uk/c2-1071-schwalbe-tires-marathon-plus.html

I like it how the Royal Mail post bikes use Schwalbe Marathon Plus - they tried everything else and found that there was a business/economic case for running with the best tyres.

Police patrol bikes are essentially mountain bikes with street tires. I have almost 30 of them that I maintain... For years, I've been using the Continental "town & country" tire on our bikes.

They have proven to be durable, have low rolling resistance, and also considerable flat resistance. One thing to avoid is any tread design with tiny cuts or "sipes. These look good but will pick up all manner of road debris (especially glass chunks) and then slowly work them right through the body of the tire.

According to most, actual tire width is not particularly important. The contact patch (that's actually in contact with the pavement) is remarkably similar regardless of tire width. Inflation pressure is more to the point.

The question about getting wheels other than 2.0 is not clear because I think from what you said earlier the tires you have now are 2.0 inches wide, not the wheel or rim. But to answer, I don't think you need new wheels or rims if you are happy with them (apart from the tires).

For the tires, your only stated criteria appears to be rolling resistance. However I'm guessing you're not racing your 29er on road. You're most likely commuting or something so puncture protection may be important, and with puncture protection weight can be a trade-off. If you state your needs better, it will be easier to answer.

Still, for street commuting and general riding I have used Schwalbe tires on both 26" and 700c wheels, and I've stuck with them because they're so good. I've also done some gentle off-road riding with them, but again I don't know if that is a need for you.

The Schwalbe website rates each of their tires for Speed, Grip, Puncture Protection and Durability http://www.schwalbetires.com/bike_tires/road_tires

I have used the Marathon Plus for years and they are brilliant for puncture resistance, and I feel they are as fast as any MTB slick I've had. I've had one puncture in 30,000km, that was a screw that jacked up into the side-wall whilst cornering. They are however hard to get on and off (I found a good trick on Youtube to do this), and they are heavy. I recently used the Marathon Dureme on a tour which are a lot lighter than the Marathon Plus and they were fast too, although a bit harder to tell how fast whilst touring.

A 35c width should be faster than a 45c in the same tire, but I switched to a 45c Marathon Plus on the back, from a 35c and I can't tell any difference in speed. The extra volume suits me as I run panniers and so the volume provides cushioning, not only to me but the wheel as well. Again, don't know if this applies to you.

Concerning the fit which you seem concerned about, since you ask if you should get new wheels, I would recommend looking at the ETRTO which is much more standard than traditional measurements which are often mixed imperial and decimal. Schwalbe lists their tires in both measures. You'll see that their 29 x 2.0 inch tires are a 50-622 ETRTO. You probably have 50-622 tires now. The main thing then is that you get a 622 ETRTO tire and that it is not too skinny for the width of your rim. Your rim manufacturer should state a minimum width tire. Make sure you are looking at the same measurement. ETRTO is the most consistent. The 700 x 35c and 700 x 45c you are talking about would be 37-622 ETRTO and 47-622 ETRTO respectively.

A new answer to an old question:

It's now 2018, and tyres have moved on a bit since the OP asked the question. I've recently been through a similar process on my 29er, as I intend to use it for a road riding holiday this year. I decided to go with a Schwalble Marathon Supreme (a light touring tyre built with top end tyre technology) in 700x40c

Here are my thoughts on the change when comparing against a high end XC tyre tubeless @25psi

1. +Less 'bounce' when climbing due to higher tyre pressure
2. +More confidence in corners on road due to bigger contact patch and no knob squirm
3. +Better feel when descending on road due to slight drop in bottom bracket height
4. +Marginal rolling speed increase on road (~0.5mph)
5. -Marginal loss of rolling speed on gravel (~0.5mph)
6. -Significant loss in comfort on gravel
7. -Significant increase in 'skittering' and decrease in cornering ability on gravel
8. -Sacrifices versatility to also tackle more challenging terrain.

I expect some of the new generation of 'gravel' tyres would sit somewhere in the middle in terms of gains/losses.

Overall, if converting a 29er to be used exclusively on road, I would recommend a fast touring tyre. However for my case at least, i will be swapping back to an XC race tyre as soon as possible as I feel the speed gains on tarmac are no-where near as great as the loss of versatility.