If you're shopping for cyclocross tires, the Donnelly brand will definitely make your short list. Donnelly offers a variety of tire types and tread shapes to suit all cyclocross riders - 4 different tire types and then 4 tread shapes to consider when making your decision.
By matching the right tread shape and tire type for your specific needs, you'll enjoy better handling, more aggressive cornering, and faster laps.
The four tread shapes are MXP, PDX, LAS, and BOS. Each is named for an airport code (Milan, Portland, Las Vegas, and Boston) and is perfectly designed for the conditions you find in those geographic regions:
These are Donnelly's traditional bicycle tires for use with inner tubes. They aren't tubeless-compatible. Their primary benefit is being very economical - a great choice for casual use or getting started, but racers will want to look to Donnelly's tubular or tubeless-ready options for better performance, so let's move on to the higher-end options.
The tubeless-ready model is the bread-and-butter of the Donnelly line. Each of the MXP, PDX, LAS, and BOS tread shapes is offered in tubeless-ready. These tires work great with sealant on modern tubeless rims for cyclocross racing and training. (I recommend Caffelatex sealant for use with tubeless 'cross tires.)
If you don't want the complexity of tubulars, but take cyclocross seriously, these are a great choice:
A primary benefit of tubeless tires is the ability to quickly change tires to suit the conditions on any single day, while using only a single wheelset. This means you can bring one wheelset to a race, but pack spare tires, and then change the tires at the venue.
The WC (World Cup) is a higher-end casing version of Donnelly's tubeless-ready models. It uses a 240 TPI casing, so it's super supple and lightweight. Additionally, some tubeless tires can exceed the UCI width limit - the PDX WC is specifically designed to comply with the tire size rules. At RideCX I recommend this tire for racers who want the best available tubeless tire for cyclocross race bikes.
As of this writing, the PDX is the only Donnelly cyclocross tread shape offered in the World Cup version:
The four Donnelly tread shapes - MXP, PDX, LAS, and BOS are each offered in a tubular tire version. This is the classic, high-end choice of professionals and enthusiast amateurs. Tubular tires are taped or glued to a tubular-specific rim, and while they require extra setup and care, they also offer the highest possible performance for enthusiast athletes, which is why tubulars are used almost without exception at the highest levels of the sport.
If you've never ridden tubulars before, you're in for a treat! Donnelly is a great choice for your first set of tubulars.
Each Donnelly tubular - regardless of tread shape - uses the same rubber coated sidewalls for durability, removable valve core (so you can easily add extenders for deep carbon rims) and are compatible with sealant for repairs.
If you're wondering "isn't the PDX a Clement tire?", you aren't alone! The tread shapes and compounds from Clement you already know and love are now sold under the Donnelly label in the United States.
Donnelly Sports re-launched the Clement line back in the United States in 2010, licensing the Clement name from Pirelli. Pirelli has since decided to start making bicycle tires, so they are now a competitor to Donnelly.
Donnelly, who created and owned design of the common tread patterns you know and trust (PDX, MXP, etc.) has as a result decided to re-launch those proven tires under the Donnelly name. Clement tires are discontinued and out of production.
You should now have the knowledge to choose the right Donnelly tires for your needs. Good luck at the 'cross races!