Motorcycle History: 26 Years Ago Today – Radial Motorcycle Tires

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Each week RideApart looks back to highlight key milestones in motorcycling history from innovations to significant model introductions to racing successes and, of course, some of the disastrous things we’d rather forget. This week it’s the 26th anniversary of radial motorcycle tires.

We’ve all come to take tire technology for granted. Despite being the one thing that separates us from the road, tires also play an absolutely crucial role in how your car or bike handles and performs.

Cars have been running radial tires since the early 1950 when Michelin first patented the concept in 1946. But it wasn’t until the 1980’s that the first ever radial tire appeared on a production motorcycle. Quite why it took that long for motorcycle tire technology to catch up with cars and trucks is still a little unclear.

There is also some debate as to precisely which tire manufacturer produced the first radial motorcycle tire. Pirelli claims it was first in 1983 with radial tires but specifically for the Honda VF1000 R introduction, while Michelin claims it was the first in 1987 offering a small range of radial tires for non-brand specific motorcycles.

Michelin still sticks by its guns and says it was first as it had a big research program launched in the early 1980s developing a radial tire that could cope with the ever-increasing performance of modern motorcycle engines.

The actual concept of a radial tire does though belong to Michelin, as its engineers came up with the idea for automotive tires in the 1930s. The premise was simple; radial tires had widely spaced metal cables placed in the sidewalls unlike cross-plys, for strength and were far better able to withstand and dissipate heat build-up. As a result, a radial tire remains softer and delivers consistently better grip under cornering. It also offers improved rider comfort and is far more durable than a cross-ply

In 1946, Michelin took out a patent for radial car tires and in 1951 the first production car – a Lancia Aurelia – was offered with Michelin radial tires as standard equipment. However, it would take Michelin until 1987 – some 36 years later – for its motorcycle tires  to reach the same level of technology.

Michelin claims its program for radial motorcycle tires began in 1981. With the majority of the development work undertaken at the race track with three-time World Champion Freddie Spencer running a single radial tire on the rear only of his Honda 500cc HRC for a season.

Freddie Spencer

Spencer said: “The introduction of the radial tire was the most important innovation of my career. A rider needs grip, feedback and longevity and the radial represented a real improvement in all three areas.

“The first thing I noticed about the radial was that it gave me much better grip and stability when cornering rapidly. I could re-accelerate sooner, which I always tried to do when racing.”

In 1984, the following season, Randy Mamola became the first ever rider to win a motorcycle Grand Prix on all radial Michelin tire shod bike.

This though was the precursor development work and build-up to Michelin launching, in 1987, a small range of production motorcycle radial tires called the A59X and M59X. But there were only five types available – two sizes for the front and three for the rear.

At the time this is what Michelin said about the A59X and M59X’s introduction:

Since 1981, Michelin has been experimenting with radial technology as applied to motorcycle tires. Before that date, sidewall rigidity had been obtained by a conventional cross-ply structure that prevented the tire from collapsing against the hub when the motorcycle tilted during cornering.

‘The first radial tires were tested in races and very quickly proved their effectiveness, enabling Gilles Burgat to win the Trial World Championship on Michelin radial tires in 1981.

Then in 1985, Freddie Spencer won titles in two different Grand Prix categories. That year, all leading speed and endurance riders competed and won on Michelin radial tires, demonstrating the validity of this architecture.’

Freddie Spencer

The next stage in radial tire development saw Michelin, in 1990, introduce silica into the rubber tire compound to resolve the early problems of finding the right balance between grip and rolling resistance, without adversely affecting the tires’ grip. By adding silica, Michelin was also able to improve a tire’s performance in the wet and improve its grip.

It took another nine years for the Michelin Pilot Sport to become the first production bike road tire to have this feature and a further six years for the Michelin Power Race, the world’s first motorcycle racing tire approved for road use to become widely available.

Dull though tire technology and development may sound, it has actually allowed bike manufacturers to look at new innovations and engineering solutions they would not have ever considered if we were still running around on cross-ply tires. Radials have allowed motorcycle engineers and designers to push the boundaries in a huge variety of areas with the result being that we are riding improved handling, faster and better engineered bikes than ever before.

Have you ever experienced a motorcycle with cross-ply tires? What would you like to see as the next innovation from the motorcycle tire industry?

Related Links:

Motorcycle History: 25 Years Ago Today – BMW First to Offer Antilock Brake System

  • james

    pah cross ply for lyf! still rollin on the sports demons on my vfr400 nc24.

  • Conrad

    I laughed way too hard at the Freddie Spencer pic in the top right corner.

  • di0genes

    Yes I can remember riding with cross ply tires, it seems just like yesterday, oh wait, it was yesterday!

    • Piglet2010

      I wish I could get radial tires for my pre-gen Ninjette and Elite 110. :(

  • Aakash

    I have bias-ply Pirelli Sport Demons on my “modern” Triumph Bonneville with spoked wheels. They are terribly unstable in high speed corners, push in low-speed corners, and jarring on the highway. I’m looking forward to upgrading to 50-year-old technology very soon with a pair of Continental radials.

    • Justin Turner

      Jesus I didn’t know Sport Demons were outdated! I switched from Avon Roadriders and I’ve been slipping all over the place!

      • disqus_SB5uBoEFy2

        Wow, yea… I put them on my KZ550. Anything that wasn’t the period-correct metzelers that were on there has to be better…

      • Aakash

        Sarcasm eh?

      • markbvt

        Avon RoadRiders are actually terrific tires for bias ply.

        • Justin Turner

          Yeah, after reading the article I spiraled into desperate tire research for an hour or so. Turns out its not a big deal, RoadRiders are killer, and I don’t have a choice anyways for 18′s. False alarm.

        • Justin Turner

          Yeah, after reading the article I spiraled into desperate tire research for an hour or so. Turns out its not a big deal, RoadRiders are killer, and I don’t have a choice anyways for 18′s. False alarm.

          • Aakash

            What tires sizes do you require for your bike?

    • pete bloggs

      They both have their plus points and negative points. The tread on bias ply tyres will last longer which means they are often used on big heavy motorcycles, Cruisers for example. Radicals handle a lot better but they will also wear out a lot quicker. Sport bikes are where the Radicals come into their own.

      It’s not just a case of saying one kind is rubbish, the other is great. It comes down to the type of riding you are doing, if you’re knee dragging on a sports bike then it’s a no brainer (radicals) if you’re cruising around on a big heavy bike at slower speeds, then the bias ply tyres are actually a better choice as they will last longer.

      • Aakash

        You sure about the lasting longer bit? Reading Mr. Watson’s article above suggests otherwise…

    • Piglet2010

      Should have taken RideApart’s advice and got the base or SE with 17-inch cast wheels and radial tires.

      • Aakash

        Naw. I picked up my ’01 for a nice deal. Plus I like the feel of a carbureted fueling system.

  • Dan

    If anyone else is wondering, the graphic below does a decent job of showing the difference between radial and bias ply tires. Line 12 is radial, lines 14 and 16 are bias-plies:

    • Piglet2010

      Looks like a patent application drawing.

  • APG7

    An article on tire selection might be kind of cool. I know shocking little about which tires to pick aside from what my mechanic suggests.

    • Tim Watson

      Good idea. We’ll look at doing something on this soon. Thanks

    • Eric Shay

      Honestly, I bought some tires last week and there was such a little price difference between compounds it made me confused.

      • Matthew

        I’ll second the request for something to help select tires.

        I’m confused about the selection between sport and touring, and sport/touring. I’m not an aggressive rider, though I do go for the weekend fun ride and I commute in the rain sometimes so I don’t know if touring is better for the cold wet rides, or sport/touring, or ?

        At what point does one make the switch from touring to sport, what influence does bike, weather and riding style matter.

        How much does tread pattern matter? For those of us that won’t be going off road but are interested in the aesthetics of the funky tread patterns that seem to be a bit oriented for off road how much of a sacrifice are we making for on-road performance in the wet and dry?

  • Harve Mil

    $.25 says this article was inspired by the craptastic stock tires on the Kawa 300.

    • Tim Watson

      Actually Harve Mil this was written before Wes;s Kawasaki review!

      • Harve Mil

        Aw, damn. I’m wrong again. That said, good article!

  • CruisingTroll

    I’d like to see a true progressive transition in multi-compound tires, rather than the “step” transitions we currently have. I know it’s possible, but I’m pretty sure it’s darn expensive to do right now, if anybody is even doing it. I doubt if anybody other than WSBK and MotoGP would be up to spending 4-5 figures per tire…. and even they probably would balk at that.

    • Mykola

      The Continental Road Attack 2 tires are advertised as “continuous-compound”. The F800GT comes fitted with them.

      • Aakash

        The Trail Attack 2 tires are also Continuous compound. It’s not the same as multi-compound though.

  • carbureted

    All of this innovation over the last 26 years to increase the grip of tires, and to celebrate, Honda goes and releases a beautiful throwback (CB1100F) with 18s that need tires in widths where only bias ply tires are available. Sad. Just sad.

    • Aakash

      Not entirely the case.

      Here are a few examples radial tires that are available in CB1100F friendly sizes:

      -Continental Trail Attack 2 rear with a Road Attack 2 front (I’ve posted a review of the Trail Attacks here:
      -Michelin Pilot Road 3 (you’ll have to run a 150 width rear)
      -Avon Storm 2 Ultra (again, 150 rear)
      -Dunlop Roadsmart

      • carbureted

        Interesting information about the Pilot Road 3s. Good to know. I have a set of PR2s, and they’re awesome.

  • Piglet2010

    To be fair, at least in the US market, radial tires did not become common until the late 1970′s on cars and not until the late 1980′s on light trucks.

  • Joe Bielski

    Bias Ply fo LIFE!!!! Cause I’m broke…… and ride the poop mobile!!!

    And I haven’t been able to find 16″ radials :( Aaaaaand yes, that’s Plasti-dip, BBQ paint and house paint on that sucker!!!