MotorcycleDaily.com – Motorcycle News, Editorials, Product Reviews and Bike Reviews

Motorcycle News, Editorials, Product Reviews and Bike Reviews

MD Product Review: Avon Viper Sport Tire

I must admit, when the editor said he had a set of sportbike tires from Avon for me to test, I was skeptical. After all, Avon as a tire company really does not figure into the typical U.S. sportbike tire buyer’s range of choices, and I don’t think I am alone when I associate the company’s image more with sport touring and touring motorcycles. Indeed, parking my Avon-shod GSX-R750 at various twisty road hangouts, the tread pattern confounded quick identification efforts by the resident riders. After reading the sidewall and seeing “Avon” they seemed even more confused, as if this were a new company.

Quite the contrary, but this reaction is not surprising, since the last measure of success Avon experienced in the world of motorcycle competition was in 1963 – a time before many present day sportbike riders/competitors were born. Avon has been making car tires since 1885, and motorcycle tires since 1911. In 1997, Avon was acquired by Cooper Tire & Rubber Company, which gave Avon access to new, high tech design & development facilities. In 2000, Avon brought out the Azaro series, a radial tire meant to combine high grip and low wear characteristics, but it never quite caught the attention of American sportbike enthusiasts. Maybe that will change with the new Viper Sport.

Basically, the Viper Sport is an all-new tire that shares little with the Azaro, other than being round and black. The Viper has a more rounded profile, using a technology Avon calls Advanced Tread Arc Combination [ATAC], which varies the tread profile across the tire for neutral handling and stability from the center to the edge of the tire. The ATAC profile is claimed to provide smoother transitions on lean angle changes, and increased stability under heavy braking. Avon also uses what they call advanced variable belt density (A-VBD), which is a circumferential Aramid belt that has closely spaced fibers in the center of the tread for stability, with more widely spaced fibers at the edge to give better compliance and hence, grip.

The tread pattern has its own acronym – EAF , or “enhanced aqua flow” – to describe its (claimed) superior water clearing ability. Adding to the tires water handling abilities is the almost obligatory high silica content, in a “high dispersability” formulation. Tying all of this together is Avon’s Enhanced Stability System [ES-System] in which the carcass, sidewalls and tread pattern work together to reduce localized flexing within the contact patch to optimize grip, durability and warm-up characteristics. That’s quite a makeover that implies competitive performance levels, but the name Avon still kinda sticks in my throat.

During installation (yes, I mount my own tires), I noticed that the carcass felt noticeably stiffer than the outgoing tires, which told me that 1) they’d be more difficult to install and 2) there would be necessary suspension adjustments. I then noticed a lack of marks showing the light spot of the tire, which complicated balancing, adding about 35 minutes to a process involving deflation and bead breaking to move the tire on the rim to a different spot, and re-inflating until minimal weight placed in one spot was achieved. Balance marks would be a great help for the bike shop and do-it-yourself installers.

Circumference measurements showed the front tire to be the same size as the outgoing tires (new when measured), while the rear tire measured 11mm greater in diameter, which would raise the axle roughly 5mm

A short initial freeway ride revealed a need for reduced compression damping (compensating for the stiffer sidewall) and, once dialed back, the ride quality was brought back into line. Heading up into the canyons at a steadily increasing pace showed the tires’ neutral and predictable character, doing exactly what I asked of them. After a few miles of break-in and increasing lean angles, I was comfortable with their grip, and started braking deeper into the corners, and applying more throttle at the exits. On smooth pavement, the steering at the front was very good, with only a slight tendency to stand up on the brakes, while the back tire handled prodigious (but smooth) throttle applications from the ’06 GSX-R750 with no protests. Transitioning from vertical to full lean, there is no tendency to fall in, and no additional input from the rider is needed until the next direction change. Running a set of esses, going from full left to full right and back showed the tires to be quick in direction changes, with no twitchiness. Once the pavement got bumpy and rippled, the tires’ stiffer carcass made itself felt, but they tracked accurately with good feedback. The occasional rock slide, pothole, or errant driver made mid-corner line changes necessary, and the Avons brushed them off as a non-event. Trail braking deep to the apex while changing my line did not phase the front, either.

I did not reach these tires’ limits on the street, simply because their abilities are beyond what the street environment can cope with, apparently providing the rider with a decent safety margin. While Avon does not market this tire for track days, it would serve a rider well in that environment, provided they did not get carried away with chasing lap times. Mount a set of Avon’s Viper Supersport, or Viper Extreme models for dedicated track-day knee dragging.

The pictures of the tires are after a spirited run up one of my local roads. They have 2100 miles on them so far, so wear should be very good for typical street sport riding and commuting. Pricing is right in line with their competition (Pirelli Diablo, Michelin Pilot Power, Bridgestone BT-014, etc.), as is their performance.

Sizing for the Viper Sport is as follows:

AV59 Front: 110/70R17, 120/60R17, 120/65R17, 120/70R17, & 130/70R16

AV60 Rear: 150/60R17, 160/60R17, 170/60R17, 180/55R17, 190/50R17, 200/50R17

As soon as other riders realize that Avon now provides a real alternative to the usual suspects available on the tire rack, I won’t be the only one riding around on them. Seems like the name “Avon” rolls right off the tongue now……….