Road Gear

Michelin introduces four new Pro4 tires

The French tire giant has an incredible research facility behind its auto and bicycle tire business


SEBRING, Florida (VN) — Michelin introduced the Pro4 platform last year with a single tire, designated “Service Course.” On Thursday at an event at the Sebring International Raceway, Michelin introduced four new members of the Pro4 family, each with unique characteristics and a lot of Michelin technology built into them.

The change from the Pro3 to the Pro4 Service Course was in the tread and was aimed improving both durability and grip, two parameters generally considered to be impossible to improve simultaneously. Improving grip generally means a softer tread compound, which wears faster, or vice versa. What Michelin did to improve both, however, was to change both the tread compound and the overall tread shape. The Pro4’s bi-compound silica and elastomer compound is tougher than that of the Pro3, and the tread shape is pointier. Both tires have smooth tread, but the taller tread profile means that when the tire is leaned over, the tire contact patch is wider. And the tougher compound wears longer. Voilá: both parameters improved.

Michelin Pro4 Comp

The change from the Pro4 Service Course to the Pro4 Comp is strictly in the casing. The Pro4 Service Course has the same 110tpi (threads per inch) nylon casing as the Pro3, but the Pro4 Comp has a thinner, more supple 150tpi, which brings the tire’s weight down from 200 grams to 180g while adding suppleness. Michelin’s tests indicate that the Pro4 Comp has seven-percent lower rolling resistance than the Pro4 Service Course.

Michelin claims that no other tire company has managed to make a 150tpi nylon casing before, and it is very complex to do so. The threads are so thin that it says that pressing rubber into the casing strung on the loom-like “calender” machine used to make most tire casings is a challenge. As a point of reference for those used to the 280-320tpi thread counts common on cotton or cotton/poly casing tubulars and open tubulars, those casings are not made on a calender and the entire tire is not molded and vulcanized like a standard clincher (which the Pro4 is). Rather, those tubular casings are made by winding the cotton or cotton-poly threads around a drum and painting liquid latex onto them. The casing is folded over itself on a bias (so are standard clincher casings) so that the two layers of threads run at 90 degrees to each other, and then it is stitched into a tube shape (tubular) or placed on a drum where beads are added (open tubular). The tread is molded and vulcanized and then hand-glued on.

Since the tread and the high-density woven puncture-protection strip under it are the same on the two tires, Michelin claims that riders will get similar durability out of the Pro4 Comp as out of the Pro4 Service Course. Of course, the 150tpi casing is thinner, because each strand of thread in it is thinner in order that 150 of them can be lined up next to each other in an inch, rather than just 110 of them. So the casing will be more delicate and less resistant to sidewall damage. On the other hand, a nylon casing is impervious to rotting, which can plague supple cotton tubulars and open tubular clinchers, and nylon is a tougher fabric in general than cotton. At 150tpi, Michelin claims its nylon casing approaches the suppleness and low rolling resistance of a 300tpi cotton casing.

The price goes up by $5 from the Pro4 Comp to the Pro4 Service Course — from $74.99 to $79.99 — and it is available now.

Michelin Pro4 Grip

This tire was made for riding in rain. It has the same casing as the Pro4 Service Course with a different tread — both in compound and in surface. The Pro4 Grip weighs 20 grams more (220g) and has 15 percent more wet grip than the Pro4 Service Course, as measured by Michelin on its wet grip track (see below). Its puncture resistance has tested 20 percent higher than the Pro4 Service Course as well.

The Pro4 Grip tread is immediately distinguishable from the other Pro4 (and indeed Pro3) models, because it is not smooth; rather, it has sipes cut into it. One may think that this would be to guide the water away, and while that effect may be there, that’s not the reason Michelin put them there. Instead, the sipes are there to remove material from the contact area so that the tire is touching the ground with higher pressure throughout its contact patch. By definition, the pressure over the contact patch will be equal to the weight borne on that tire, divided by the surface area of the contact patch. Reduce the area of the contact patch, and you increase the pressure in psi measured at any point on the contact patch.

Michelin claims that if you were to do this type of siping on most tire treads, it wouldn’t work due to the type of tread compound used. Its new compound has a higher durometer (that may surprise you), which thus deforms less to also keep the surface contact area lower and thus reduce hydroplaning.

Why is puncture resistance important on a rain tire? We all know that we get more punctures riding in the rain than in dry conditions. I had always assumed this was simply because the rain washed more debris onto the road, and that the debris stayed on the tire through more revolutions in the wet, rather than just falling off as it might have in dry conditions. While those things may be true, Michelin engineers pointed out that the water acts as a lubricant to allow sharp things to penetrate the tread more easily. So, those engineers put a wider puncture-protection strip that is made out of tougher woven aramid (i.e., Kevlar) fibers, rather than nylon.

Like the Pro4 Comp, the Pro4 Grip sells for $79.99 and is available now.

Michelin Pro4 Limited

The Pro4 Limited uses the same casing and tread as the Pro4 Comp, but eliminates the puncture-protection belt to save 15 grams. Michelin claims that this change drops the rolling resistance of the 165g Pro4 Limited by 20 percent over the Pro4 Comp, due to the reduction in mass and the elimination of the densely-woven nylon belt.

Like the Pro4 Comp and Pro4 Grip, the Pro4 Limited will sell for $79.99. It will be available in about a month. We did not test it.

Michelin Pro4 Tubular

Michelin has not offered a tubular in the U.S. in over a decade. This new tubular will have a 290tpi cotton/aramid casing and will sell for $119.99. In 23mm, it will weigh 280g, and in 25mm, the weight will be 295g. Ag2r La Mondiale rode it in Paris-Roubaix and the Tour de France in 2012.

The puncture-protection strip and tread are hand glued on. The tubular has a different tread compound than the other Pro4 tires; since the different tire shape results in a different shape to the contact patch, a tread compound more suited to that has been chosen. Michelin claims that in a round shape of a tubular tire, the cotton casing is more flexible than a nylon casing, thus the choice of cotton with aramid fibers interspersed for increased cut resistance. Look for our testing of this tire in the future.

Test Riding

We rode the Pro4 Grip on an 18-mile road loop near Sebring, and then on the Sebring International Raceway track. The Pro4 Comp we rode only on the track, and neither the Pro4 Limited nor the Pro4 tubular were available for test. The Pro4 Grip was a noticeably stiffer tire than a supple tire like a high-thread-count tubular. Its cornering grip seemed fine on the dry roads here as well as on the rubber-coated track, but there was not a drop of water on any road around on which to test its wet grip.

The Pro4 Comp rode very nicely. It was obviously very light and felt snappy when accelerating. It also felt quite supple on the bumpy racetrack, which is actually built out of an air force landing strip from WWII. It is made out of 20-foot deep blocks of concrete floating on a sand bed to support landing B-52s. Some of the wider longitudinal cracks in it did give one a bit of pause when riding their direction on 23mm tires. The Pro4 Comp was noticeably more comfortable than the Pro4 Grip riding this bumpy surface and hitting the rumble-strip and curbed track edges as well. It took the sharp hairpin on the track very nicely — plenty of cornering grip.

The Company

Michelin moved its bicycle tire production from France to Thailand over five years ago with the inception of the Pro3 tire. It has built an entire wing at Lion Tyres to make only its tires, bringing in its own equipment and technology, while still being able to capitalize on low Thai labor costs.

Michelin is not heavily invested in bike racing and for that reason is perhaps less chosen by the high-end, race-oriented crowd than it otherwise might be. Last year, its only WorldTour team was Ag2r La Mondiale, but now that team is sponsored by Schwalbe, leaving the French tire giant without a top-end pro team. The product presentation on Thursday highlighted the relationship with Ag2r La Mondiale as being critical in product development… Rather than having a traditional supplier relationship with pro teams, in which the supplier pays the team to use its equipment, Michelin USA’s Ralph Cronin said, “Michelin feels that the teams should come to us, since we have the best product, which we do.”

The bottom line is that Michelin is an engineering company at heart, not a marketing company. It chooses to spend only a small percentage of its budget on marketing, and in a time of belt-tightening, its scales back marketing efforts before engineering efforts. The company employs 6,000 people worldwide in research and development alone, spending almost a billion dollars per year on R&D. While its bicycle division is a tiny percentage of the overall company, its bicycle engineers can draw on the vast technical resources and knowledge base of the company in designing its tires. For example, it has computer simulation software that simulates performance and looks at changes in tire shape under various conditions, something it claims sets it aside from other bicycle tire companies.

Michelin is also quick to remind that it started out as a bicycle-tire company, before the inception of the automobile. Once the car came along and the company started making car tires, it produced the green Michelin maps and the red Michelin Guide to restaurants as a way to get people to drive more and hence to buy more tires.

Michelin claims that its investment in R&D dwarfs that of other tire companies that do both automobile and bicycle tires. Its main engineering campus in Ladoux, France, covers 1,112 acres, has 79 separate buildings and 41km of test tracks of 19 different types. For example, it has one employee whose entire job is to ensure that the entire wet test track is covered with precisely the correct depth of water (varying from 2mm to 8mm)!

Sure, most of the Ladoux test tracks are automobile-oriented, but when Michelin says that one bike tire grips better in the wet than another, it has the data to back it up. Rather than having only the perceptions of a test rider to learn from, it instead has data that says, “at X speed, tire A loses grip at Y angle with Z depth of water.” This data comes via a telemetrically-wired bicycle with accelerometers, angle sensors, and speed sensors, as well as an adjustable third outrigger wheel so the rider need not fall to the pavement every time his tires break free of the wet surface. So, when Michelin says that a given tire has certain characteristics, you might be inclined to believe it and give some of the new Pro4s a try. It claims to have used 50 different test machines and subjected tires to 250,000km of testing in developing its Pro4 line.