The best information I have seen on this topic is contained in this thread:

http://forums.mtbr.com/xc-racing-training/wide-rims-low-tire-pressures-992972-2.html

In summary, light weight should not be the only consideration in your tire purchase (rolling resistance is arguably just as important).

You do not need a tubeless-specific tire, although a good argument could be made for them being less prone to catastrophic failures. I ran Kenda Karmas for years racing XC with no problems. Then I ripped a sidewall (not racing) and that tire got sewed up, booted, and I couldn't use it tubeless anymore.

After reading the content here and evaluating the options, I am now on a Schwalbe Thunder Burt 2.1 in the rear and a Racing Ralph 2.25 in the front. I ride rigid and the courses are not technical. This damn TB sure has worn out quickly though. I will probably put another RaRa on the back, or maybe try out a pair of Conti Race Kings.

Bicycle Rolling Resistance | Rolling Resistance Tests

Hope this helps.

 

I was also a fan of the Kenda Klimax back in the day. I currently run Specialized Renegades for the lightest and fastest tubeless that I can find. 1.95 in the past worked fine, now I'm running the 2.3s on a fully rigid. Dropped the fork for the easy courses and bumped the tire up a size for comfort

 

I'm a huge fan of tubeless setups and I think most tire choices depend on the trails, how you use the bike, and personal preference. And tubeless or not, there is always a tradeoff between weight and durability.

IMO, the biggest determination for running a tire tubeless is volume and when you do get a puncture if there is sufficient volume of air to seal it quickly. If it doesn't seal quickly you could break the bead and then you're probably back to running a tube out on the trail.

As for TR ready tires, if I have an option I go with the cheaper or lighter non-TR ready tire. I've had good luck getting non-TR ready tires to seal. Sometimes they take some work getting the bead to seat (hint: use extra rim tape or even rim strips for loosely fitting tires) and they usually take a couple rides to fully seal. Some are better than others but when they're sealed you're good until you have to remove the tire. Be sure to maintain sealant as it dries and sometimes Stan's will separate.

 

Thanks for the link to that thread. Lots of interesting info in there (and it gets a bit heated at the end!)

What is kind of interesting to me is how much talk there is of rolling resistance but at the same time everyone trying to get their pressure as low as possible. The Crr data shows that higher pressures have less rolling resistance. With that in mind, you'd think the quest would be to find the highest pressure you could get away with.

As I said, I come from a technical riding background and now ride fairly tame XCO race courses (Ontario Cups) so I don't feel that I need more cornering traction at all. I am willing to give up a bit of traction for a faster rolling tire. Therefore it seems I should run higher pressures, not lower. Can anyone convince me that the gains in traction are more important than lower rolling resistance? That seems to be just a given fact in these discussions but I've never seen or read anything to convince me that it's true.

 

I am on the same page with you here. I probably run tubless tires on what is now considered to be the high side of XC race pressures - 25 psi in front and 27 psi in the back, and that is even lower than what I used to run clear up to 40 psi in the back.

I recently made a little drop from about 30/27 psi to my current 27/25 psi, and I thought the change was a barely noticeable improvement in cornering with no noticeable difference in rolling resistance. But that is really hard to characterize, and I doubt it had any affect whatsoever on my overall time.

I really think you have to do a lot of experimentation on your own soil, with your own bike, and with you as the independent rider, to come to a good conclusion on the particular tires you want to use and the pressure you want to run them at. For me that traction/rolling resistance tradeoff really only became noticeable on my particular race track which is hardpack with some sandy sections. I noticed on some sections that my rear wheel was starting to slide a just a tiny bit around the corners and that if I lowered the pressure that seemed to help a bit. It also happens that my local race track has A LOT of high speed turns. If that were not the case I would probably be running different pressures and/or tires.

So I have never really found that there is one perfect race tire for everybody, even if you narrow it down to very specific riding/racing/bike parameters. The way I am approaching the question is to get a reasonable set of tires that would likely work well for me given my experience, riding style, bike setup, and terrain. I plan to try those tires out over time until I settle on that one best combination for me.

 

I've had good luck with S-works Renegades and Conti Race King RS for a rear and front on the right course. X-King RS or S-works Fast Track for front.

 

just another couple data points.

On my Specialized Carve rigid single speed I have 2 sets of wheels/tires. One is a set of tubeless RaRas on the stock Specialized Stout rims. The other is a set of Velocity P35s laced to XT hubs with a Bonty Chupacabra 29x3.0 in front and a Bonty Team XR4 2.3 in back. I am always faster with the bigger/heavier combo, no matter how smooth or rough, flat or hilly, straight or twisty, etc...

On my Canfield Yelli Screamy hardtail(old XC race bike) I switched from 29er WTB KOM i23 rims laced to X9 hubs with Kenda Slant 6 2.2s to a set of 27.5 WTB Scraper i45 rims,straight gauge spokes and the same X9 hubs with WTB Trailblazer 2.8s. I am faster everywhere with the super heavy 27.5+ combo, both ups and downs.

Another slightly funny point. I am only marginally slower with my 26x4.7 Trek Farley 7 rigid fatbike.

My newish XC race bike is a 2014 Spearfish with the KOM i23s laced to BHS hubs and I run either the Kenda Slant 6 2.2(most often) or Bonty Team XR2 2.3 depending on dirt conditions.

 

I race mostly in dirt and roots, short steep uphills, tight corners, a little to a lot of mud.

In these conditions I am heavily in favor of Schwalbe. The Thunder Burt 2.1 is pretty darn light and its side knobs will save you, unlike super light competitors from Maxxis, Specialized, or Continental.

The Rocket Ron has more knob per gram than any other racing tire; they feel like cheating with velcro. It's best race tire in the mud.

In my opinion the Racing Ralph is a mediocre tire, even though a lot of people prefer it. A nice way of saying mediocre is that it's the best all-arounder; of that I'd agree.

I'd set up a new mountain biker on Nobby Nics, or throw them on my bike for a vacation trip out West.

Schwalbe's tires are so light, fast, yet grippy because the standard "Evo" casing is really intended for race day only. Use Raceguard or Snakeskin if you value your money. I've made it through several 100-milers with one set of Snakeskin series Thunder Burts, but I've flatted with Evolution series Rocket Rons multiple times in XC races before I learned my lesson.