- Written by Carole Nash Editor
- Created: 08 April 2014
In the Pilot Road 3, Michelin has been producing the world’s best-selling sports / tourer tyre for around three years. It was hailed as a great all-rounder at the time and still sells extremely well, so why would Michelin decide to risk this by replacing their class winner with a newcomer so soon? Can the new tyre be good enough to steal the Road 3’s crown? I was invited to Seville in Spain to find out.
I suppose it’s obvious that, on a tyre designed for the masses to use on regular road bikes, the main thrust of Michelin’s focus would be safety. Following a short film to introduce the tyre, the briefing started almost instantly with the three figures that would crop up time and again throughout the day.
- 17% shorter stopping distances in the wet over its nearest rival
- 20% improved longevity over the Pilot Road 3
- 50 degree Celsius thermal range (the tyre works equally well from -5degC to 45degC)
Front and rear Pilot Road 4 showing XST technology (thins slits with holes)
The tyres come in three variants – the regular Road 4, for regular sports tourers over 600CC; the Road 4 GT for larger machines; and the Road 4 Trail for heavy, high torque trail riding touring bikes. We didn’t test the Trail but the differences between each tyre are mainly the way the dual compound is laid out across the width of the tyre, the softness of the compound used and the carcass technology – explained later in this review.
Tread pattern - 2CT (Dual Compound Technology)
The standard and GT versions have the same tread layout, with the front offering a wide 40% band of medium compound across the middle and 20% of soft compound on the shoulders. The rear sports a hard compound across 20% of the middle to help with longevity and the medium compound covering 40% each side of this. The trail version is the same front and rear, with a 60% band of medium compound across the middle and 20% of soft compound on the shoulders. It all makes a lot of sense when you think about it.
The magic of the tyres’ wet weather performance is in the tread pattern. My initial view of the pattern was that it is not as visually pleasing as many other tyres on the market, with the Pirelli Angel, for example, playing strongly on the ‘look’ of the pattern. This can be a big selling point, but given that the best-selling Pilot Road 3 isn’t staggeringly beautiful in this reviewer’s eyes, you have to assume that all of the other factors still play a very big part in the purchasing decision.
‘Sea to land’ ratio, XST and XST+ (Cross Sipe Technology)
With the introduction of Michelin’s patented Sipe technology, the tyre has two weapons in its arsenal against water. The regular way of removing water is to simply gouge channels for it to escape under pressure – the more grooves there are, the more space for water to escape, but the less rubber is planted on the road. It’s a balancing act between wet and dry grip and the longevity of the tyre.
On the Road 4, Michelin refers to this as the ‘sea to land’ ratio with the groove being the sea and the rubber that makes contact with the road being the land. The ratios have changed slightly between the Road 3 and the Road 4. The middle band is where the greatest proportion of braking will occur so this is the most important place to remove water, and the front Road 4 offers over one fifth (20.4) of its surface area to that function. The rear is slightly less, given that it is less important during braking – 16.7% of it is sea.
The intermediate section between the middle band and the shoulder has seen an increase in this ratio, with the front gaining a 0.2% and the rear gaining 0.6%. It’s not a lot in number terms but I’m assuming it’s significant when you consider how much more water those channels can now remove at speed. In theory this should make cornering in the wet a safer proposition.
At steeper lean angles Michelin have realised that there is very little need to remove water, as the shoulders are not going to get touched in wet weather. The ratio has been drastically reduced by over 3% to offer more rubber to the track in dry conditions. It all makes a lot of sense!
The XST+ sipes are thin slits cut across the tyre width to aid water removal and have chamfers cut at the leading edge to help increase tyre life.
Now, those Sipes, or XST (Cross Sipe Technology) which Michelin is so proud of, aid in the water removal process by acting as a kind of blade to cut into the water surface and squeeze the water from one area of the tyre (the contact patch) to another area of the tyre where there is a large reservoir to release the water, thus creating a drier surface for the tyre to make contact with. With XST+ there is a chamfered leading edge of these delicate-looking Sipes to help prevent premature wearing under braking and increase tyre life. Again, it makes a lot of sense in theory.
Carcass – 2AT (Dual Angle Technology)
As mentioned previously, Michelin was at the forefront of radial tyre design and, as well as aiding in comfort, it offered allowed tyres to move away from the air filled sausages that preceded them and to retain a specific shape by applying strands of steel or other materials across the profile of the carcass at approximately 90 degrees. Moving on from the basic radial tyre were the Bias layout, where a criss-cross of strands are laid at more acute angles and help to give the tyre far more rigidity for carrying heavier loads. Both technologies have benefits over the other in different situations.
Amalgamating radial and bias technology to create 2AT
Michelin has worked for five years to amalgamate these technologies and make use of both properties in the same product. They have included this in the GT version of the Road 4 to allow heavier bikes to benefit from the rigidity needed for the extra weight and the comfort provided by the radial system. Given that new machinery had to be designed to create each new prototype, it is no surprise that this whole process took five years, but it has paid off, with BMW Motorrad opting to have the tyre fitted as OEM on the R1200RT with no model-specific alterations. The tyre that comes with the BMW can be bought off the shelf for any other bike.
We were guided to a specially prepared strip near the track that looked like garage floor paint with a constant stream of water flowing over it. Most riders would recognise the surface as something similar to a soggy zebra crossing - a scary place to be when you have to grab a handful of front brake.
The briefing explained that the GPS measuring equipment would start measuring distance when the bike came down to 40kph and stop measuring when the speed reduced to 10kph. We get up to 50kph before hitting the slippery stuff, pull in the clutch at the start of it and grab a fistful of right hand while ignoring the back brake... then wait while the ABS and tyres worked their magic.
The whole thing feels pretty alien with the front juddering and squirming below you and the ABS obviously stopping everything from getting too out of shape, but the exercise was to prove the effectiveness of the tyres, not the ABS.
For each delegate, the first two runs were on Metzelers with the last two runs reserved for the new Pilot Road 4s. There was a distinct, but indescribable difference between the two with regards to 'feel'. I'm convinced the bike fitted with Road 4s moved side to side less and felt more surefooted but this is a ‘seat of pants’ observation. Everyone had different descriptions for the sensation. The figures spoke for themselves though... we all stopped several meters shorter on the Michelins. And not just a meter or two - it sliced around nine meters off all of the tests!
Several delegates checked the tyre pressures across all bikes and they were all the same, leaving the tread pattern and compound as the main difference between them. The impressive figures marched out by Michelin can't be directly verified as the second tyre was not their main competitor, but the results were very impressive all the same and we left with little doubt that the Dekra-verified wet braking results really were achievable.
The next workshop would put this to the test in a more realistic scenario!
When you are taught to ride a motorbike you are taught that braking on corners is bad. Braking with your front brake on corners is worse and braking with your front brake on wet roads is an absolute no-no! So when we were faced with a chicane on a wet surface that we had to emergency brake on I felt a sharp tingle run down my spine.
The whole wet test would include a cornering section, a straight with 110kph emergency stop and the dreaded chicane. Our first man went out and fearlessly blitzed all of the tests without giving it a second thought. And when it came to my go I equally found that although my brain screamed at me to not be so stupid the bike had absolutely no problem with any of it. The ABS activated on both braking tests but there were no other signs that the tyre was struggling in any way. There was complete composure from the front end with no squirming like we had on the painted surface, and the weight transfer to the wrists and handlebars told me that the bike was stopping very quickly indeed. With no rear brake used at all there was no fear of that coming round to meet me either.
Tyre confidence track test
The final test! A dry circuit and two very different bikes to prove that the tyres behave the same regardless of the weight on them or the speed you are going. The bikes used were the old model R1200RT for the weighty tourer and the Yamaha MT-07 for the lightweight comparison.
The test involved four guided laps of a relatively short circuit with each lap getting progressively faster to increase lean angle and confidence in the tyres. Obviously the little Yamaha was always going to be fine with this sort of test as it weighs virtually nothing, but the Beemer was a different beast and not designed for track riding at all. My experience earlier in the day on the roads proved to me that the brand new model was a very capable machine so I trusted that Michelin wouldn’t be asking us to do anything that they weren’t sure the bikes could do.
I went out on the Yamaha first and true to form, the little bike dove into corners confidently and accelerated away with no hint of squirminess at the rear end. Despite the buffeting from being unfaired, the high speed straight felt planted and smooth. A very comfortable and enjoyable ride all round.
Then I jumped (or heaved) myself onto the BMW. Looking out through the windshield past the array of dials, buttons and stereo speakers I had to wonder why anyone would take a bike this size around a circuit. She fired up with that Boxer sideways thump – something her younger sister doesn’t do, I might add – and surged forward out of the pit lane. The first corner came quite slowly and it felt comfortable, as did the second, third, etc. The first lap ended and all was well. The second lap was a little faster but the bike felt just as planted as during the first lap. Third lap came and went and we were starting to have to really push the bikes into the floor. The landscape looks a bit odd at those angles through all of that dashboard and windshield!
The fourth lap was pretty much flat out. The big old girl was being thrown from side to side and it felt like I could have put castors on the panniers to help me get round, but they weren’t needed. The ride was still comfortable and secure and the bike could have done so much more in the hands of someone more qualified than me, but it felt good. Very good!
I entered the pit lane, came to a halt and sat there for a second. I’m pretty sure I giggled a bit as well. That bike should not be able to do what it just did, and particularly not on tyres designed for fat touring road bikes. Quite amazing.
The figures touted by manufacturers across the entire motor industry are often seen as just that – figures. They probably don’t mean much in the real world and, quite frankly, a lot of people don’t take them too seriously.
The Pilot Road 4 GT will be an OEM option on the BMW R1200RT
Michelin gave us three figures at the beginning of these tests – 17% shorter stopping distances in the wet, 20% longer tyre life and 50degC thermal range. Michelin have done all of the tests on the longevity so I have to take their word for that at this stage. Our tests were all done in the mid 20degC Seville sunshine so, again, I can’t say how they will fair in Dubai or Greenland. What I can say is that they have done an amazing job with their wet weather abilities while retaining amazing levels of grip in the dry.
Would I personally swap my beloved Pirelli Angels for a set of these? Yes. And I probably will. They’re a small premium to pay over the older Pirellis but assuming the tyre lasts a bit longer than the additional wet grip has come at almost no extra charge. Definitely worth it!