Guest Pete McCrary Posted June 17, 2007 Share Posted June 17, 2007 What exactly are the differences between an H rated tire and a Z rated tire other than an H tire is rated for 130 mph and a Z tire rated for 150 mph? Will an H rated tire suddenly "explode" at 131 mph? There are a few tires that are available in either the H rated version or the Z rated version. I went from Z rated tires on my KTM Duke II (I know it's a completely different animal than a VFR) to H rated tires. I could not believe the difference! Z rated tires on the Duke would take 20 miles of aggressive (and scary riding) to get warm to the touch. H rated tires would be good and hot and very sticky in 10 miles. Stuck like cat doo-doo in shag carpet when hot. Extremely confidence inspiring. I recently read an article on another web site where a German magazine took an R-1 Yamaha and ran it on a 100 mile loop in the German mountains. The first run was with "touring" type tires. The second was with high performance street tires. The third was with race tires. They ran several temp checks throughout the run. The only tire that they could get up to proper operating temp on the street was the touring type tire which in turn offered the greatest grip on the street. I'm coming to the conclusion that there is a "right" tire for the "right" place. Race or super performance tires don't work as well on the street as we might think - but they work great for track days. Are we "over tiring" our bikes with the latest and greatest race proven technology tires when we can't get them hot enough to work like they should? Any input appreciated. Link to comment Share on other sites More sharing options...
Member Contributer Chev Posted June 17, 2007 Member Contributer Share Posted June 17, 2007 interesting discussion. I don't ahve a lot to add, but what i do have is purely guesses and rumors. If I remember correctly, tires rated at higher speeds tend to be built firmer, to resist deformation at extreme RPMs (I think this is in the steel belt construction). This could be why some touring tires "might" get up to temperature faster. :beer: Link to comment Share on other sites More sharing options...
enzed_viffer Posted June 17, 2007 Share Posted June 17, 2007 The difference in rating refers to their ability to withstand sustained use at that speed. So if an "H" rated tyre was used occasionally at 150 mph, it would be OK. And yes, you're right about people "over-tiring" their bikes. Race tyres/tires are designed to heat up quickly and will only withstand a few heat cycles before they "go off" and lose their stickiness, whereas a road tire takes longer to heat up (doesn't need to be as sticky anyway) and can withstand repeated heating/cooling without going hard. Eventually they do (go hard) anyway, so a tire can be at the end of its life before it's down to the wear bars. Link to comment Share on other sites More sharing options...
Guest Posted June 17, 2007 Share Posted June 17, 2007 I guess the specific combination I'm kicking around is using an H rated Pirelli Diablo on the front and the new Corsa Diablo on the rear (Z rated). I came across the H rated Diablo under unique circumstances. They're available in Europe but not in the US. Link to comment Share on other sites More sharing options...
enzed_viffer Posted June 18, 2007 Share Posted June 18, 2007 I guess the specific combination I'm kicking around is using an H rated Pirelli Diablo on the front and the new Corsa Diablo on the rear (Z rated). I came across the H rated Diablo under unique circumstances. They're available in Europe but not in the US. Hmmmm.... It's just my personal preference (so you can take my opinion with a pinch of salt) but I'd rather have a stickier tyre/tire on the front than the back. Presumably the Corsa is a race tyre/tire, and therefore supposedly stickier? Link to comment Share on other sites More sharing options...
Member Contributer jeremy556 Posted June 18, 2007 Member Contributer Share Posted June 18, 2007 I don’t know what to tell you about H vs Z rated tires as I have never run any non-Z rated MC tires. If the German testers couldn’t get a sport tire up to temperature they have the pressure too high or they are riding way too slow. Sport tires will get sticky enough to have every bit of gravel and dirt from the road sticking to them after a leisurely ride or even just riding at high speed in a straight line because of carcass flex. You are correct in there are right tires for the right place, that is why there are ST tires, sport tires, and race tires. Link to comment Share on other sites More sharing options...
Guest Posted June 18, 2007 Share Posted June 18, 2007 Enzed Viffer: That's my point exactly - it is sticker if you can get it up to the proper temp it was designed for. My experience here lately has been that a hot touring or H rated tire is in reality gripper than a cool high performance tire. I just don't think you (read I) can get a high performance tire up to the operating temps it was designed for riding in the mountains or similar situations. Ever got off your bike, pulled your gloves off and felt of the tires? A properly working tire should be so hot you can barely touch it after a blast through the twisties. On my Duke, I can get H rated tires so hot I can barely touch them. Z rated tires are slightly warm to the touch. And the rear tire is always a lot hotter than the front tire. Plain and simple, I'm trying to get more heat into my front tire without going to ridicuouly (sp?) low air pressures. Just my 2 cents. Pete Link to comment Share on other sites More sharing options...
V4 Rosso Posted June 18, 2007 Share Posted June 18, 2007 Jeremy, Pete is probably refering to a test conducted by Motorrad. As he mentiones, the test was done on the street, not the track. And they'll use the factory recommended tire pressure, as that is what most ( I am one of them) will put in their tires and is suitable for almost any type of street riding (two up, packed with luggage or solo). They do however post recommended tire pressure for spirited solo riding (twisties) or the track: example On the VFR with ST tires they mention to use minimum of 2,3bar front and 2.4bar rear for spirited solo riding. In this test they took 7 different ST tires to the track but had to keep the speed rather low as to not get the tire temperature above 50C, the temperature they measured when they took the ST tire through the mountain loop. On a sidenote: They mention they used the VFR as a test mule as the current generation of ST tires are so sticky when leaned over that the only ST bike suitable to test these tires at max lean angle is the VFR. Link to comment Share on other sites More sharing options...
Member Contributer FotoMoto Posted June 18, 2007 Member Contributer Share Posted June 18, 2007 My experience here lately has been that a hot touring or H rated tire is in reality gripper than a cool high performance tire. Interesting topic. My experience here where the roads get really warm is that a sport tire sticks better than an ST model. The ST tire gets greasy and slips on less than perfect pavement while the sport will hook up. Check out the June issue of Bike magazine for a great Q&A with several tire experts. Link to comment Share on other sites More sharing options...
Baileyrock Posted June 18, 2007 Share Posted June 18, 2007 I guess the specific combination I'm kicking around is using an H rated Pirelli Diablo on the front and the new Corsa Diablo on the rear (Z rated). I came across the H rated Diablo under unique circumstances. They're available in Europe but not in the US. Hmmmm.... It's just my personal preference (so you can take my opinion with a pinch of salt) but I'd rather have a stickier tyre/tire on the front than the back. Presumably the Corsa is a race tyre/tire, and therefore supposedly stickier? You want the stickier tire on the front always , much better to have the rear slip than front IMO! I wouldn't really worry about the speed rating if your not racing or over 100 mph constantly. :goofy: Heat isn't always a good thing in tires either, get certain tires to hot and they turn to Sh*t. A ST tire will Never provide better grip than a Sport tire if proper pressures are used for both. B) Link to comment Share on other sites More sharing options...
Guest COTU Posted June 18, 2007 Share Posted June 18, 2007 I went from Z rated tires on my KTM Duke II (I know it's a completely different animal than a VFR) to H rated tires. I could not believe the difference! Z rated tires on the Duke would take 20 miles of aggressive (and scary riding) to get warm to the touch. H rated tires would be good and hot and very sticky in 10 miles. Stuck like cat doo-doo in shag carpet when hot. Extremely confidence inspiring. I assume the H rated tires were new, but how old were the Z rated you removed? Link to comment Share on other sites More sharing options...
Guest Posted June 18, 2007 Share Posted June 18, 2007 On the Duke I was running brand new Pilot Powers and then switched over to brand new Pirelli Diablo (H rated in the rear) with an Avon ProExtreme DOT Rain in the front (H rated). Awesome combination. The problem with H rated Pirelli Diablos is you have to order them from Germany. The price is good but the shipping kills you. Link to comment Share on other sites More sharing options...
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