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MD Product Review: Pirelli Diablo High Performance Street Sport Radial

Pirelli Diablo – Front

Among the consumable items associated with a motorcycle, the tires probably have the most profound effect on performance and rider feel. This point was recently driven home, just two weeks after spooning on a new set on my sportbike. Murphy took up residence, puncturing and slashing the rear tire into submission. I repaired the puncture with an internal patch, but the cut was too much. Barely 800 miles had passed and I was now faced with shelling out yet more $$$ for a replacement. Grrrrr….

Then the phone rang. It was Dirck, calling to see if I would be interested in trying out a set of the Pirelli Diablo sport street tires. Barely containing my glee, I responded in the affirmative, and shortly after, the Pirellis first graced the rims of the 2001 Honda F4i, and are currently serving duty on my 2001 Honda CBR929RR in the garage. On both bikes, their performance has been noteworthy, particularly on the 929.

The Diablo is Pirelli’s newest offering in the cutthroat arena of sport bike performance street rubber. Combining the latest tire technology with the technology developed on their own Supercorsa DOT racing tire from 2002-2003, Pirelli set out to achieve four major design goals – dry grip, handling, wet performance and overall ‘balance’.

Recent tire developments have resulted in compounds that warm quicker and work well over a wider temperature range while resisting overheating, and wet weather performance has improved with increased silica content. Pirelli is no different in this regard, touting “maximum silica content”, but specifics on the compound recipe remain secret.

The main reason for increased wet-performance is not so much because of silica content, but more from what Pirelli terms “ICS” or, Ideal Contour Shaping. This process is responsible for a front tire that in the wet Pirelli says, “cleans and dries” the road surface for the rear tire to track through and creates a maximized contact patch efficiency between the front and rear tires, for perfectly matched handling traits in the wet or dry.

That’s what they say, but how do they work? Quite well, as I have found out. Unfortunately, I was not able to make it to the track, which Pirelli feels this tire is up to, so I am sure that I was not at the performance limits of the tire on the street. On both the F4i (stock suspension) and the 929 (aftermarket suspension front & rear), the tires exhibited very stable handling traits, especially over some of the more gnarly surfaces found on the Malibu hillside roads. They worked well with the suspension to absorb bumps and gaps while aiding in keeping the bike planted and pointed in the right direction.

Pirelli Diablo – Rear

In the faster curves found on the roads of the Angeles National Forest, they were plenty stable. Steering speed, while a touch slower and heavier than other tires in this class, remains acceptably quick, without being twitchy or overly sensitive. With the 929 and its reputation for being a bit lively, a rider may find this to be an asset. Traction was abundant, and allowed regular scraping of the footpegs on the F4i. My 929 is setup not to scrape (on the street) and so while nothing touched down, it is not due to any performance shortage from the tires.

While braking in both a straight line and entering a corner, the bike maintained a precise line without additional input.

There isn’t any rain falling out here in SoCal, and there’s a song that says so, so I have nothing to report on their wet weather prowess. But monitoring conversations of east-coast riders who have used them in the wet reveals that they do very well in these conditions, also.

What has really caught my attention about these tires is how they have worn, or not worn, actually. With any tire, as miles accumulate the rear tire tends to lose its profile, or “squares off”. Handling deteriorates as the condition worsens. The front generally suffers its own profile degradation, with “cupping”, or “scaling” of the tread, which can be felt as you run your fingers around the circumference of the tire, along with visible wear just off center as you look at its profile.

These tires, after 6700 miles, look like tires with half that number, and I have complete confidence of another 2000 miles, maybe more, to come. Although there is a little squaring of the rear tire, it isn’t enough to affect handling the smallest bit. The front tire has retained its ‘as new’ profile, with no cupping or scaling evident, so steering is as precise and predictable as when new.

That said, my riding style does not include wheelies (ever – I’m not good at them), or drag race-style starts, but I do strive for solid drives out of a corner. I rode everything from downtown stop-and-go traffic, to freeway riding, to canyon carving, and these tires ate up the miles, wherever they were. Given the tires’ performance in the curvy stuff, I’d say that the mileage and relative lack of wear I’ve experienced is quite an achievement, but your mileage may vary.

I highly recommend these tires to the sporting crowd, and even the sport-touring riders, because of the potential life span. Pirelli rates them acceptable for a track day, and I agree, as long as the speeds don’t edge too closely to actual race speeds. Their capabilities may be stretched a bit thin by the go-fast “junkies’, and the fast guys would be better served by mounting the Diablo Corsas, which are geared for the track environment.

Suggested retail prices provided by Pirelli list the front in the range of $149.95-$154.95, and the rear $185.95-$244.95, but hardly anyone pays retail these days, so query your favorite tire vendor (hopefully, a local shop) and give them a try when your current skins reach their ‘change by’ date.