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Review: Michelin Pilot Street Radial

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Michelin is a household brand. Founded in 1889, it is also one of the oldest surviving major brands in the world. Like many other tyre manufacturers, Michelin’s success is derived through a clever mix of pioneering efforts, innovation and marketing prowess. If you did not know, the two founders of Michelin, André and Édouard, pioneered the use of air-filled (aka pneumatic) tyres for the automobile in 1895, fitted them into a car they made themselves (i.e. L’Eclair), and competed in the 1895 Paris-Bordeaux race (the first removable pneumatic tyres, also made by the brothers, were used on a bicycle race, and won at the 1891 Paris–Brest–Paris).

Fast forward to 1946, Michelin also introduced arguably the most significant innovation in tyre history: radial tyres. Michelin’s radial motorcycle tyres, however, were not introduced until 1987 (i.e. A59X & M59X).

Now that we’ve gotten that bit of history out of the way, I felt that the most prudent manner of writing a tyre review for the masses would be to compose the article more comprehensively. Hence, the first thing you will need to know about the tyre is its terminology. This allows you to fully understand (and appreciate) the differences and improvements made to the venerable tyre through the years. The figure below shows the major parts that make up a tyre.

TyreAnatomy1

A brief anatomy of an average car tyre. Terminology applies to all types of tyres (including motorcycle tyres).

The inner (or carcass) plies of the tyres before Michelin introduced the radial construction, were criss-crossed. These tyres were called bias-ply tyres. Prior to the introduction of radial-ply tyres, bias-ply tyres were the only option available. Despite some benefits compared to the radial construction, bias-ply tyres have all but gone out of favour. The figure below shows the difference between a bias-ply tyre and radial-ply tyre.

BiasvsRadial1

The inner/carcass plies of the bias-ply tyre are angled (normally between 30-45 degrees in relation to the beads, while the plies in a radial-ply tyre are perpendicular (90°). Note that the top/cap plies are not directly connected to the inner/carcass plies in the radial-ply construction.

Bias-ply versus Radial-ply
Why are radial-ply tyres preferred over bias-ply tyres? The answer lies in its structure. Bias-ply tyres have overlapping inner plies, criss-crossing each other. This makes the tyre a bit thicker, and hence, more prone to heating up (when the tyres are in contact with the ground). Radial-ply tyres, on the other hand, have its inner plies running from bead to bead. Other plies above (outer plies) are not directly connected to the inner plies (unlike bias-ply tyres). This means that they are able to function separately, yielding a more controllable ride. As such, a thinner construction can be made, giving a more flexible (i.e. pliant) overall tyre.

Also, because of the inherent design in bias-ply tyres, the tread and beads are interconnected. Thus, any load on the tyres (be it from the inside: air-pressure, or outside: heavy vehicle load) will inevitably affect the contact patch of the tyre on the ground. Essentially, radial-ply tyres allow for: 1) lower fuel consumption, 2) increased traction (especially when manoeuvring), and 3) better service life (in part due to lower heat damage versus bias-ply tyres).

Background
Coming down to the matter at hand, the Michelin Pilot Street Radial, introduced at the end of 2013 in Malaysia, comes as a logical upgrade for the Pilot Street (which is made using a bias-ply construction). The new tyres were made available due to the increasing popularity of 250cc bikes, in south-east Asia and around the world. You could say that Michelin has developed the Street Radial specifically for this category of motorcycles (although plans for larger sizes were already in the works).

BD-PilotStreet-34-110 copy

Front tyres of the Michelin Pilot Street Radial (110/70 17-inches)

BD-PilotStreet-140-34 copy

Rear tyres of the Michelin Pilot Street Radial (140/70 17-inches)

Michelin claims that its Pilot Street Radial’s unique selling propositions (USPs) were its radial construction, better handling (and hence, safety), and superior durability. There is a strong relationship between the radial construction and tyre handling properties. To maximise the radial-ply tyre’s abilities, Michelin has slightly changed its profile, making it slightly sharper in the middle. This allows the motorcycle equipped with the radial tyre to have more responsive turn-to-turn capabilities (i.e. sharper lean). The shoulder of the tyre has also been pushed further towards the sidewalls to enable a steeper lean angle. The figure below illustrates the difference between the bias-ply Street and the radial-ply Street Radial.

Presentation_Pilot Street Radial_Eng_V2_30_Page_13 copy

The differences between Michelin’s bias-ply Pilot Street and radial-ply Pilot Street Radial are minimal, but significant

In terms of safety, which is a derivative of its handling abilities, Michelin has made sure that its tyres’ treads have been optimised for both wet and dry riding (tread design carried over from Michelin’s popular Pilot Sport Touring Radial). The grooves on the treads gradually increase from the middle, giving better water-dispersal capabilities on wet roads (3mm in the middle, opening up to 5mm at the 20° lean angle mark, and onto 6mm at the far sides). Although made entirely from a medium-hard compound, the Pilot Street Radial’s all-silica rubber means that its wet grip is still top-notch. In fact, the Pilot Street Radial came out tops in wet grip tests conducted by the German inspection authority Deutscher Kraftfahrzeug-Überwachungs-Verein (DEKRA) in 2012 (versus the Bridgestone Battlax BT92 Radial, Bridgestone Battlax BT90 Radial tyres, and Pirelli Sport Demon).

Groove1

13% of the total grooves cover the middle of the tyre, presumably to enhance dry grip (i.e. higher tyre-ground contact), while 23% of the total grooves are placed at the 20°-25° lean angles on each side for better wet grip. The rest of the groove allocation are for lean angles more than 25°

Additionally, do note that the grooves on the front tyre is reversed from the usual water-displacing design. I asked Michelin about this, and they explained that this is due to the fact that the front tyres normally bear the brunt of braking, and its design is meant to facilitate better traction under braking. Makes sense, I guess, although I do not know how the water-displacement feature will work (since the grooves are now reversed).

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The Pilot Street Radial also offers an even longer service life compared to the Pilot Street. This is due to two factors: 1) its radial construction, and 2) its tweaked silica compound rubber. Michelin also compared its Street Radial to its closest competitor: the Pirelli Sport Demon (Street Radial lasted longer by 30%; testing done by Brazil’s Instituto Mauá de Tecnologia).

Testing

Michelin Pilot Street Radial (1)

The Ninja 250R with its previous tyres: the Pirelli Diablo Rosso II

The test mule for the Michelin Pilot Street Radial is a hardly-used 2013 Kawasaki Ninja 250R, with 10,192 kilometres on the odometer.

Michelin Pilot Street Radial (3)

Rear tyres are worn, thanks to the DRII’s medium rubber compound (soft compound on the outer edges). I will expect the Pilot Street Radials to last longer, since it has a harder compound compared to the DRII’s. So, the question now would be: How much longer?

Its previous tyres were the much-acclaimed Pirelli Diablo Rosso II (110/70 R17 front, 140/70 R17 rear). Based on its previous specifications, I opted to go for the same size of tyres (original, out-of-factory-spec tyres from Kawasaki were 130/70 R17 rear).

Michelin Pilot Street Radial (5)

Notice the wear pattern only extends to the 25° lean angle. I have yet to possess the ability or the testicle size to ride it out all the way to the chicken strips (i.e. outermost lean angles). Maybe I can do it with the Pilot Street Radials.

The outgoing Diablo Rosso II’s were arguably the best dry road-going tyres in its class. Its grip was immense, even at the limits of adhesion. I had no issues knee-dragging the Ninja, be it on the highway or the curvy mountain roads. The tyres stay planted, even over undulating terrain. IMHO, it would take a lot for the Pilot Street Radial to depose the DRII. There were, however, two caveats to the DRII: 1) its wet grip is not as stellar as I hoped it would be (then again, the tyre was not meant to be used on dripping-wet roads), and 2) its service life (at 10,000km, it looked particularly worn, especially the rear tyre).

Therefore, what the Pilot Street Radial lacked in outright dry grip, I would be hoping for it to make it back in wet grip and longevity.

Fitting

Michelin Pilot Street Radial (7)

Here the Ninja gets lovingly manhandled, and its wheels stripped (cue ’90s porn music)

The tyres were taken to a nearby workshop to be fitted. Other than a slight issue with filling the tyres with air (which was soon rectified), I had no problems. Any reputable motorcycle workshop should be able to fit the tyres satisfactorily.

Michelin Pilot Street Radial (12)

Its been quite some time since I last witnessed the holy ritual of removing the tyre protectors

First Impressions (10,192km +0km)

Michelin Pilot Street Radial (14)

The test mule with its new tyres installed. If I hadn’t known better, I think she winked at me

The Pilot Street Radials are very much like the Diablo Rosso II’s in that they react somewhat alike in any given situation.

Michelin Pilot Street Radial (17)

Note the “Made in Thailand” mark. From experience, tyres made in SEA aren’t normally up to mark (looking at you, Duro). Michelin, however, has been known to be particularly anal about QC, so we’ll just have to find out.

The tyres are still new, and have not been broken in yet (e.g. release lubricants still on tyres), so I limited the cornering to more benign angles (read: I was being a wuss).

Michelin Pilot Street Radial (15)

The tread design isn’t as masculine or futuristic as the DRII’s, but hey, whatever gets the job done in the wet

I was expecting the dry grip to be a little less than the DRII’s, but so far, it has performed rather well, surpassing my expectations.

Michelin Pilot Street Radial (20)

There! Front arrow goes one way, grooves designed the other way

Knowing that it will be dry (and hot) season soon, I took the opportunity to ride the bike out after a heavy downpour. Its wet grip is definitely superior to that of the DRII, even before being completely broken in.

Overall, the Street Radial’s feedback is good, which I assume to be due to the radial construction and the slightly thinner sidewalls. Lean effort is about the same as the DRII’s, although the DRII’s gave me more feedback during cornering.

It will be fascinating to test the tyres out after the break-in period, which I have set at 1,000 kilometres. Stay tuned to the next installments of this tyre review. I shall be making a new article after the +1,000km, +5,000km, and +10,000km marks.

About Andrew Lee

Andrew is a commercial photographer by day and speed demon by night. Don't let his pleasant, approachable demeanour fool you, as he's an incredible fast driver on the circuit! Andrew is a man of many talents (some hidden). He often baffles many with his uncanny ability to stay awake for an inhuman number of days, then disappears. For hours. TCG labels him “Comatose Man” for his nocturnal endeavours and sleep super powers.

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