Three New Species of Vipers Discovered in England

Avon Motorcycle Tires
Melksham UK
Pembrey, Wales

Pirelli doesn’t even have a Queen.

In American roadracing Avon is known primarily as a supplier for race tires for vintage bikes. In Europe Avon is known primarily as a premium performance car tire manufacturer with a heavy focus on supplying race tires for cars. They build 8,000 or so car tires to every 1,000 motorcycle tires each day in their original 100 year old Melksham factory.

I was allowed one picture inside the Avon tire factory. This is it. What you have here is a conveyor belt
that doubles as a scale. The man is tossing bags of raw materials (silica, carbon black, sulfur, synthetic rubber) in the correct proportions by weight. Once the ingredients are properly proportioned they all
get shot into a mixer and made into a sheet of rubber to be used for tread or sidewall.

Avon is currently owned by American company Cooper Tire & Rubber Company (NYSE: CTB). Cooper has been investing heavily in Avon’s future and is planning on building a new radial motorcycle tire factory in Melksham. Avon currently employs about 1,000 people at their Melksham plant.

‘Avon’ is apparently an old Anglo-Saxon word for ‘river’. If the Romans had stuck around not only would
modern day cuisine be substantially improved in England but we would be riding on ‘Fluvius’ tires.

Two of those people design motorcycle tires. With the neat graphics, fancy renderings and slick acronyms my imagination conjured up teams of engineers undertaking massive research projects to build new motorcycle tires. After meeting Avon’s Pete McNally that seems hopelessly naïve and over complicated.

They have a couple of guys who look at Avon’s past construction, study other brands, design tires, have the factory produce a couple, take them to the track and have their test riders thrash on them. They gather data, get a thumbs up or down from the test riders, then revisit the design or begin construction.

And that is for the entire line of motorcycle tires, not just their performance tires. This allows a creative process that is equal parts art and science. Instead of having a product designed by a committee that could result in a lowest common denominator bland tire, you get a product that is exactly how a small group of enthusiasts want it to be. If your tastes are similar to their tastes you are sitting pretty. Fortunately Pete is my kind of guy.

The new top end range of sporting tires from Avon is the “Viper” in three different variations: Sport, Supersport and (with a very un-British like superlative) the Xtreme. Avon has studiously avoided the use of the label “DOT Race Tire” for any of these variations and instead has stuck with the “Sport riding and track day” tire moniker. When comparing their Xtreme blend they do claim it stacks up next to other brands’ pure race tires.

Vipers in Wales, alert St. Patrick.

Avon has put some interesting ideas to work in the Viper range. All three versions use a fairly flat profile that offers a massive contact patch and most lean angles. All three versions use the Advanced Variable Belt Density in the rear tires. Rather than building dual compound tires, Avon has built a rear carcass that is stiffer in the middle and more flexible on the edges. The stiff center gives the tire high stability and a cooler running center tread. The edges of the tire deform more creating a larger contact patch but also allowing the edge of the tire to flex more. Tire flex is an excellent way to build up heat in a tread and, if the compound is properly formulated, a tire that runs hotter on the edges and cooler in the center will function like a dual compound tire even though it is actually a single rubber.

The compound itself is a high silica compound with fine grain dispersion that Avon refers to as SIO2-HD. In a tremendous oversimplification of tire compounds, Carbon Black gives maximum traction in dry conditions with high temperatures but also wears quickly. Silica gives much better traction at lower temperatures and also works in damp or wet conditions. Silica compounds tend to wear much slower than Carbon compounds. Tire engineers are, therefore, endlessly playing with different blends of these along with the thickness of the tread rubber (thick rubber runs hotter, thinner rubber runs cooler) and carcass, etc.

In general, high silica tires (and there are a couple others out there from other manufactures) tend to come up to temperature really quickly, work well on dry or damp tracks, work really well at cooler temperatures and wear really well but, ultimately, will not have the last bit of grip for a pure race lap. They also have a tendency to get too hot if they are ridden really hard on an abrasive track in hot weather. What is really hard? Say front running expert club times at your local track.

The differences between the three versions are: the Sport is the base tire with a medium compound; the Supersport has a softer compound; and the Xtreme has the same compound as the Supersport but less negative tread area. Less tread means more rubber so the Xtreme offers a bit more grip and, in theory, tire life at the expense of its water dispersion abilities.

The Sport and Supersports are available in all the usual tire sizes as well as the /65 profile front utilized by Kawasaki. The Xtreme is only available in big bike sizes (180 and 190 rears) and uses a slightly taller rear section (55 instead of the more commonplace 50) to preserve the neutral profile across the wide 190 tire. The taller tire will also slightly quicken steering by raising the rear of the bike.

I rode a variety of modern sporting 600s and 1000s at the Pembrey racetrack in Wales. Being only a few miles from the temperamental Irish sea our track day started with a soaking wet and chilly track which eventually dried to being just a chilly track. The track was almost all right-handers with just a single double apex left-hand sweeper. I was wearing brand new custom leathers and my favorite one off painted helmet (thanks McDermott) and I was eying the wet track and imagining how the left side of the tire would never come up to temp while figuring out where exactly I was going to end up in the tire wall when I was spat off.

As it turned out these conditions suited the tires perfectly, almost as if they had been designed by guys that lived about two hours away and been built in a quasi-local factory. On the wet track the tires delivered predictable handling and ample grip even at reduced lean angles. I was not quite willing to go for the knee down in the wet action but if I was wearing someone else’s leathers (and using someone else’s collar bone) I might have been tempted.

Nice grip in the damp but puddles are still puddles.

I had enough confidence to allow me to ride aggressively enough to make numerous passes on other riders on my first laps around a track I had never seen before. Making passes in those conditions means late, off throttle corrections, trail braking on wet pavement and generally wandering around searching for the correct line. The tires handled all of it with no complaints. I was riding tense waiting for the front end to tuck through the fourth gear high-speed sweeper or the long cold left but the front end wiggles never came. The grip, for those conditions, was excellent.

The next session was even more treacherous. Not only was I running with another rider for the whole session (a leading cause of idiocy) but a heavy mist rolled in half way through the session so our dryish line became increasingly damp as our session continued. Of course, neither one of us wanted to be the rider that backed off even as the track grew wetter and wetter but both of us finished the session intact, whole and without ever finding the limits of the tires.

The third session was mostly dry and the tires continued to work very well. Even though it was a cloudy and cool day and we were not using warmers I could be knee down on the third turn without any cold tire wiggles. The thick silica rubber quickly came up to temperature and held the heat allowing me to charge the only left-hand turn without concern for warm up.

The ZX-10 could spin up the rear pretty easily in all the low gear turns but, to be fair, it can spin up most tires pretty easily. The rear tires coped with the bhp of the 600s without any complaints. Although the front tire never budged it also did not give a great deal of feedback. This could have been due to the stock set-ups on the bikes (and I never rode the same bike twice so I never bothered to put a tune on the suspension) or it could have been that I was just unfamiliar with the feel. The grip was there but the corner speed was largely based on building familiarity with rather than innate feel from the tire.

This one could spin up the rear, but, to be fair, the ZX-10 can spin up just about any rear. 

Mostly I rode bikes fitted with the Supersport compound. The bikes fitted with the Sport compound did feel slightly more wiggly (i.e., ‘some’ compared to ‘none’) but the bikes fitted with the sport tires also had lesser quality suspension (SV, Triumph) than the bikes with the Supersport tires so some of the wiggles could have been bike induced.

There were no Xtremes at the event.

After riding all day all the tires on the bikes still looked and performed well. None of the journalists in attendance complained of a tire going off on any of the bikes and a visual inspection showed only slight wear. This was after a day of riding well in excess of the speed encountered in the expert groups of track day participants.

After I got home I was asked by some of my motorcycle enthusiast friends how I would place the Avons. The following statements are a blend of past experience with Avon as well as my experiences with other high silica tires and these in particular. Avons tend to wear really well and these tires work well both cool or hot and on damp or dry tracks. My one concern has more to do with silica tires in general and not these in particular. On a blistering hot track (Willow, Talladega, etc) the thick silica compound might not be able to shed heat quickly enough with a fast rider. That determination will have to be made by others at a later date (unless I am invited to test Avons at a blisteringly hot track in which case I will let you know). However, if you are a track day enthusiast or a performance street rider and don’t want to mess around with tire warmers, worrying about matching compounds to track, worrying about heat cycles or other such fickleness associated with full tilt race tires and you don’t want to have to sit in the pits if the track is wet, these tires would be an excellent choice.

Due to limitations on official photography inside the factory, instead of photos of the bead wire machine, the
carcasses winding machines, the tire assembly machines, the tread molds, the guy putting the tread onto the
carcasses and pallets of tires getting ready for shipment to Seattle, you get a picture of Stonehenge. Enjoy.



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