Product Review: Vittoria Diamante Pro-Radiale Tire

The Diamante Pro Radiale tire is extremely supple and durable thanks to a radial casing to improve the ride quality with a lower rolling resistance compared to the previous model. We were given a set to try out and logged enough miles to get a good feel for these high-performance tires. The Diamante has always been a well performing tire that was overshadowed by the Vittoria Open Corsa models. Not any more though. The Daimante Pro Radiale version ups the performance, making it a competitive alternative to the less robust, more race minded Open Corsa. I was excited to try these tires out because I’m a big fan of radial casings. To understand the advantages of a radial casing it’s important to understand how tires are made. We won’t go into too much detail here, but a video is provided below for your enjoyment.

To the left is an illustration of how a radial casing travels over objects vs standard casings. Above right you can see an expanded view of the Diamante Pro Radiale.

So why didn’t I show you a Vittoria video? Well the only Vittoria videos online show how a tubular and open tubular (such as the Open Corsa Evo CX) are made. However, those tires are not vulcanized so the process doesn’t represent how a Diamante Pro-Radiale is made. In the construction of the tire carcass, the nylon fibers are mated to the rubber. The orientation of those fibers is crucial to how the tire rides. Most tires have the fibers oriented at a 30-60 degree angle from the direction of rotation. In order for a casing to be called radial, the nylon fibers must be laid up in a near 90 degree orientation to the direction of rotation. This eliminates the fibers from rubbing each other when they are folded over and consequently reduces rolling resistance and makes the tire more supple. In the automotive market, a full radial is so supple that it doesn’t provide enough structure for the rubber so belts are inserted to help the tire hold form, hence the name “steel belted radial.” In the bicycle world the same is true except that adding steel belts defeats the purpose of making a lightweight bicycle tire. Vittoria thus orients the fibers at an 85 degree angle giving the tire enough structure to hold shape under load, but still gaining the benefits of radial technology.

Vittoria also is the leader in thread count for its tire carcasses. The more threads there are the less need for rubber and consequently the lighter the tire is. Diamante Pro Radiale tires have a true 250 tpi (threads per inch) which means that in one layer of fibers there are 250 threads per square inch. This makes the Pro Radiale extremely supple. So supple that Vittoria released it as a 22c and a 24c instead of the more common 23c and 25c. The reason being that a Diamante Pro-Radiale 22c is so supple that it rides like a 23c. The same goes for the 24 in relation to a standard 25.

I was given a set of 22c Diamante Pro-Radiales to try out and can confirm that they are possibly the most supple tires I have ever ridden. I put about 600 miles on the tires and came away very impressed. Everything Vittoria claims about the suppleness of this tire is true. I would even speculate they may be more supple than the Corsa tires, though that is purely subjective on my part. Another side benefit of the Pro Radiale is it’s incredibly light weight. My tires weighed out to 187 grams each. Combined with Vittoria’s own latex tubes, these tires will help your wheels spin up faster than you may be used to. Lastly, 600 miles isn’t enough to thoroughly test a tire’s durability, but I can confidently say these tires are more durable than the Corsa models. The tread is much more resistant to cuts and slashes, as proven by the lack of slits or cuts in my tires. The last time I rode Open Corsa tires they only lasted 4 rides before they had more cuts in the tread than I was comfortable with. That’s not to say the Open Corsa isn’t an excellent tire, it is… for racing. The tread on the Open Corsa is super sticky, so it picks up more road debris, a natural consequence of having more grip. I would say that comparing the GP 4000 S to the Diamante Pro Radiale is a fair comparison. The durability is on par. The GP 4000 S might have a little more grip with its black chili compound, but the Diamante Pro-Radiale unquestionably rides better.

We would encourage anyone who is looking for excellent ride quality to try out the Diamante Pro-Radiale tires. If you ride one of the current crop of wider rims, go with the 24c model. If you are running Mavic Open Pro rims or another 19mm rim, the 22c will give you better cornering. The 24c will work fine if you’re not doing any crits or taking a lot of hard corners at speed. My personal recommendation is a 22c up front for better cornering with a 24c model on the rear to provide extra comfort. Diamante Pro-Radiale tires can be purchased through Art’s Cyclery, and don’t forget that all tires are 20% off with the purchase of a wheelset.