The tread on the conto race king pros is not very aggressive, and the side knobs are not really any bigger than the center knobs.
So from a grip perspective, they are limited to certain kinds of trail conditions or riding style.
I’ve used them twice for Leadville, and they’re great for that. But find them a little sketchy on my local singletrack descents. Certainly not as confidence inspiring as even the new XR3s (which have small center knobs, but aggressive side knobs)
Have you compared them to Ikons? I’m racing a marathon Saturday and already loaded up the Contis 
Haven’t ridden Ikons, so don’t have a direct comparison.
They’ll likely be fine for a marathon, where it’s hours in the saddle of steady power output that count.
In a shorter XC race where you might be pushing it hard on a descent is where they’d find their shortcomings I think.
Also depends on the surface. They’re fine on hardback. Not great on loose over hard. And bad on loose dust.
Pirelli rear specific and Pirelli mixed terrain up front, both in 2.2. Best tyres I’ve used in a long time, superb grip in the dry, rocky and incredibly dusty trails we have here in Central Victoria, Australia. They are also very tough, our trails are notoriously tough on tyres.
This year I ran 2.25” Schwalbe Rocket Ron’s front and back. Next year I’ll probably give Ralph and Ray combo a try.
I want to use the Aspen 2.4, but I don’t think that one is coming out any time soon. 
I’ll be running the Aspen 2.25 at most every race, but I may try the Rekon Race at Vail Lake and Bonelli down in SoCal. I think the Rekon Race rolls faster (honestly don’t know), but the locked-in feel you get when on the cornering knobs is a bit more confidence inspiring than with the Aspen. It’s a bit drifty when you’re not on the cornering knobs, but I think this could be a good option for the concrete-like dirt and off-cambers in SoCal.
I’m going to do an informal “rolling test” with these tires this spring to see if there is any measurable difference.
I’ll also be testing tire inserts this year to see if they are worth the weight increase of ~200g and be familiar with how they perform and how I’ll have to change my suspension and tire pressure just in case nationals is a mudder. You could save a ton of energy in slick conditions by running really low tire pressure with an insert.
I know this company is working on an even lighter race model, but here are the inserts I am considering running: https://www.merlincycles.com/ptn-pepis-tyre-noodles-pair-29-122813.html
Have you found a place that sells the tire inserts (PTN) in the US?
Not yet, but I think they take a week or two to arrive from Merlin.
Just out of curiosity, if the rekon race is more confidence inspiring, and possibly faster, why are you choosing the aspen?
The Rekon Race is only more confidence inspiring when you are leaned over and the shoulder knobs (cornering knobs) are digging in. Everywhere else, it is not as predictable and consistent as the Aspens.
The thing that most people like about the Aspens is their predictability – they always do what you think they should do. But, they do have their limits, and the Rekon Race just bites a bit harder when you are really leaned over.
Also, I only think the Rekon Race rolls faster out of looks. I thought they felt faster when I ran them this summer for a bit, but it’s impossible for me to ward out a placebo effect there. They look faster with the tiny little knobs, but looks don’t equal actual performance.
Thanks for the more in depth review. With every company coming out with so many xc options it gets really hard to choose even within one company
Good to know, the Forkasters come on the new bike so will try them out before the BC Bike race to see if they will be good enough.
It will be great to know how you get on with the inserts Jonathon as I was in 2 minds whether or not to use them for the BC Bike Race. I was looking at cushcore XC but the PTNs are cheaper and about the same weight.
Ran 2.4 ardent up front and 2.35 ikon rear. Loved this setup. We have a decent amount of sketchy/gnarly Jeep road descents in a series in CO and this pair was great.
I may go back to some 2.25 aspens or imo a for the upcoming year.
That’s definitely an ideal race for those inserts. Traction and flat protection!
I think the Cushcore setup is about ~140g per wheel while the PTN is ~100g per wheel, but I bet the difference is imperceptible. PTN look a bit easier to set up, but Cushcore may give better performance. I may try both!
Looking forward to hearing how they go. @Jonathan
They came on my Orbea Oiz 120mm… Forekaster front and Ardent Race rear. It was a wettish stage race and I figured what the hell…
Honestly, I’m not sure I’d do it again. The bike was still new to me (actually my first serious trails on it because of the way shipping worked out) so I don’t regret it, but all in all, the Forekaster is a pretty aggressive tire.
I’ve mainly run Maxxis on my XC bike the last few years, but I’be been so impressed riding Terreno Drys on my cyclocross bike on my local trails that I’m definitely going to look into Vittoria’s MTB tyres. Only problem is they’re a little harder to get here.
Take it how you will since he’s sponsored so obviously that skews his publicly stated opinions, but nino said in a recent interview there’s no need for foam inserts with xc wheels getting so wide. Just being the messenger here
I should have taken your advice and taken the time to swap out these tires to something else. The race course was the most “turny” of any I have ridden and this was not a great tire choice for that type of track. I was even significantly drifting the rear tire in corners which for me was a first.