Fitting new tires to your bike has the same nervous anticipation of a blind date. You’re wondering from the get-go whether the relationship will work out, or if it might be a terrible mismatch. Or will I embarrass myself and fall flat on my face?
And just like that dating situation, you want to believe the hype – whether it’s dished up by your friend promising you that “this girl has a lot more goin’ on than a good personality, trust me bro’,” or whether it’s the tire company spokesman promising you that “these are way better tires in all conditions than the beat-up hoops you are currently running.” Still, those first few miles (or minutes) are always charged with trepidation, tentativeness and emotional turmoil.
The case of these new-for-2004 Metzeler Z6 sport-touring tires fits the above analogy precisely. I’ve had plenty of miles on their previous generation Z4 tires, which have been and continue to be steady sellers for Metzeler. But I, like some others have reported, was let down by how much they slowed the steering of most any bike to which they were fitted, how they tended to stand up under braking and how long they took to warm up and grip at sporting lean angles. The overall result was that they caused the rider to want to hold back from full-tilt sport riding.
Case in point: a stock 2002 Honda Interceptor owned by a friend of mine, fitted with Z4s. He’s always been a relatively quick rider, but when we’d go for one of our nice little Sunday morning banzai runs between radar traps, he’d fall behind as though he was riding a ’48 Knucklehead with balloon whitewalls. When I test-rode it, the thing was a total bull in the twisties – heavy, slow, and plodding to the point that we kept double-checking tire pressures, steering head bearings and messed a lot with the available suspension adjustment, all to no avail.
His ‘Ceptor handled a lot worse than a similar Honda press fleet bike I previously had tested, and immeasurably crappier than the quick, fun and responsive 1998 VFR that I used to own. As a last resort, I talked him into spooning on a set of Dunlop 208s and, you guessed it, the bike was transformed. It seemed as if the relationship between the Z4’s design and that of the VFR is as oil is to water.
So I was heartened to learn at the press intro for the new Z6 – held in unseasonably cold Ojai, California – that the current VFR was the main bike used for developing and testing the new Z6. I felt like I had a little secret up my sleeve here and it would be tough for Metzeler to pull one over on me. But unlike some manufacturers who stand blithely behind anything they have for sale, the mix of Italians and Americans on hand from Metzeler were quite forthcoming about the Z4’s problems. They actually listened to complaints from customers and journalists, and the problems I described were addressed with the new Z6.
Science is our friend
It’s nice to know that while we are eating burgers, watching cable TV and recklessly burning the world’s fossil fuels, there are scientists working ’round the clock to make better tires for our motorcycles. To develop a sport-touring tire that inherently must be a compromise because of its varied applications, they went deep – developing a new way to make the tires from scratch, something they call “quadraplex extrusion.” It’s a new technique that allows them to bond the tread, the undertread and the sidewall compounds to the radial steel belt simultaneously. According to Metzeler, this enhances the likelihood that the total tire works as a consistent piece, with less chance of delamination or balance inconsistencies.
The steel belt itself is the same zero-degree technology Metzeler has used for years. It sounds fancy, but it simply means that the belt cords (in this case thin steel cables) are wound around the carcass in the same direction that the tire will roll. The windings themselves are spaced differently depending on where they are on the carcass (closer to the center or to the sidewalls). The windings are spaced wider at the edges to allow that part of the tread to be more compliant, which means that you get the most grip from the biggest contact patch when you need it most – knee-down and on the gas.
Compared to the Z4 at a 20-degree lean angle, the Z6 offers 5% better grip. At 30 degrees it offers 20% better grip. At 40 degree it offers 22% more grip. Once you get past 40 degrees, you’d better know what the hell you are doing.
Okay, how about two more bits of innovation before your eyes completely glaze over: CMT and FCM. CMT stands for Contour Modeling Technology, basically some sort of algorithm that allows the engineers to make miniscule but ultimately helpful changes in the tire’s profile to optimize handling at any lean angle. The old MEZ4 had a very flat profile that contributed to its slow handling. These Z6’s are for lack of a better term, “Dunlop-ish,” striking a nice balance that feels instantly neutral.
Where the Z4 had too much tour and not enough sport in its equation for my taste (trading off dry grip for extended life), this Z6 is definitely an improvement. The Metzeler science guys tell us that it grips commensurately better than the Z4 as you increase lean angle.
Metzeler chalks this up to the Finite Carbon Matrix (FCM), a fresh new carbon black compound some guys cooked up in the lab so you could go faster and fall less. Nice of ’em, huh? Of course, there’s no way this intrepid reporter could possibly vouch for the accuracy of those percentages, but the ass-o-meter says these tires do stick better in the dry. They don’t give you that planted-on rails-wick-it-up sensation you get from full zoot sport-compound tires (try the Rennsport for that), but a good rider with Z6s spooned on will definitely be able to attain very quick corner speeds, reasonably good grip under hard braking, and lots more miles of high-speed straight running.
They also work better in the rain. You can thank three very soggy testers in Europe who put 100,000 miles on public roads and the Metzeler test track. Near the end of the tire’s development phase, they were out there hand cutting the length, depth, width and curve of the tread siping to try to optimize wet grip and water channeling. For the most comprehensive testing possible, Metzeler would run the prototype Z6s in the cold rain in Europe, then pull them off and send them to Metzeler’s identical test track in Brazil to test them in the hot South American rain.
Metzeler is making two different carcass constructions based on the weight of the bike: under or over 500 lbs. wet. For either carcass, Metzeler recommends 34 psi in the front Z6 and 38 psi in the rear.
Metzeler’s R&D work was a success. I tested the Z6s in some of the snottiest rain SoCal has had in years (the same downpours that caused those deadly mudslides) I was glad these were on and not some supersport rubber. Not that those are bad in the cold/wet, but these are that much better. If you ride a lot in the wet, you need these tires.
Okay, so cut to today. It’s January in Los Angeles. It was 77 degrees and dry, like “I’m thirsty” all-day kind of dry. Hammering along a familiar road, I felt the front end push a bit under hard trail-braking, and the engine on my bike felt magically more powerful than on the Dunlops because it was just a tad easier to get the rear end loose on the gas. As a result, I rode slower than usual. I’m not talking Rebel 250 slower, I’m talking maybe 5% slower in 2nd-gear corners and 10% slower in 3rd- or 4th-gear corners. Not a lot, but I could feel it.
The drive to produce better tires for us is obviously market-driven, as the manufacturers know that we all talk to each other about how our tires work and we rely on their grip way more than our compatriots on four wheels. Metzeler is especially susceptible to this insular word of mouth, as they produce nothing but motorcycle tires.
The buzz about their Z4 (among everyone except, interestingly, Beemerphiles) was that it had lots of limitations. I think the buzz about the Z6 is gonna be different. Is it enough to want to go to the bike shop and pay to have my still-good Dunlops put back on? Well, maybe in June. I think there might still be rain in the forecast…