How do Dunlop 208 GP-A's behave in high heat?

[tilejerky]

OK, here's the situation. I'm going to the west coast to visit a friend, and we decided that we should do some track days together while I'm out there. So I'll be riding a 2003 Ducati 749S at Thunderhill on July 1 & 2. I'm told that the temps there can be well over 100 degrees in July.

The bike currently has Dunlop 208 GP-A's mounted on it, with one track day on them. I know that these are considered to be very good tires, and that a lot of racers and fast guys really like them. Personally, I've never had good experiences with Dunlops, and am a bit anxious about running tires that I don't know at a track that I don't know on a bike that I don't know. Mostly, I'm concerned about the potentially high temps, because I've read that the Dunlops can get a bit greasy in high heat.

I've got the option of mounting either Pirelli Corsa III's or Supercorsas instead, but it seems like a waste to dismount perfectly good tires. Even though I know that the Corsa III's aren't nearly as good as the 208 GP-A's, I've run three track days on them them on my bike and have absolute faith in them. I've not run supercorsas, but my buddy swears by them.

Basically I'm looking for feedback from anyone that's run the Dunlops in high heat, because I'd rather not waste tires on my buddy's bike that I'll only be riding for a few days.

GSXR Racer Mike, I'd really like to get your feedback on this, as I know that you've run Dunlops (I've read quite a few of your responses in the threads that I've searched through). I almost asked this question in your return to racing thread, but didn't want to hijack.

Anyway, can anyone steer me in the right direction? Oh, and I should also mention that I'm not blazing fast, I'd say Intermediate mid-pack is where I'm at. Here's a pic for reference:

[Mmelmann]

cough SUPERCORSA PRO'S cough Man, excuse me. Sorry.

No really, I'm regretting the switch to Dunlop. When I raced back in 2000 I ran the old 207 GP's and they were okay. I had to step away from riding for a while and I got back in the game a couple of years ago. Once I switched over to Pirrelli I found my tire company to love. I ran Supercorsa Pros out at Willow Springs and I loved them. It was last year about July and the ambient temps got up to 106 deg F. They were great. I even ran them every weekend out at Palomar Mountain and they were so plush and communicable.

My buddy was running a 208 one weekend for the first time and I remember him blaming the tire for his subsequent crash. Maybe the tire had been cooked one to many times before (he put a used 208 GP on the front) but I just know that he wasn't expecting the decreased amount of grip and feedback.

I know this info probably doesn't help much. Sorry.

[tilejerky]

Originally Posted by Mmelmann

My buddy was running a 208 one weekend for the first time and I remember him blaming the tire for his subsequent crash. Maybe the tire had been cooked one to many times before (he put a used 208 GP on the front) but I just know that he wasn't expecting the decreased amount of grip and feedback.

See, this is the kind of stuff that I'm always reading about Dunlops. People that like them really love them, but the negative experiences tend to be really negative.

The thing is, I'm kind of nervous about crashing my buddy's bike. I'd rather have new tires mounted than risk crashing the bike. I can't imagine how much $ it would cost to fix even a low-speed lowside on a Ducati 749S, and I don't want to know.

I also realize that half of people's attitudes about tires is superstition, but that's not to say that it's unimportant. If you've got faith in the tires, then you're ahead of the game. Even if it's only psychological, if it helps you to ride better and be safer, then it's worthwhile.

Part of my personal superstition about Dunlops is based on riding their stock street tires and having the bike slip. Also, I've only crashed once, at my first track day ever, and it was on Dunlops (on an SV650). The crash wasn't the fault of the tires, but, irrational as it is, I'm still a bit biased against them.

Really, I'm looking for something concrete to base my decision on, rather than just going on "feeling".

[Mmelmann]

Here was the shot when he was using 208's.http://www.rickclemson.com/Photo_Det...352&EventID=73<----He has just lost the front end here and entering a low side.

He slid right into the camraman about .45823 seconds later. I was just outside of the shot on when it happened. I couldn't believe what I just saw. It totally chopped blocked the cameraman and thank God he was okay.

It sucks that tires and tire changes have to cost so much. It just may be worth the added security and piece of mind though. Just saying.

[tilejerky]

Not to pile on your buddy that crashed, but what was he doing running so fast on public streets? He's carrying so much lean angle that he's inviting a lowside.

I kind of wonder if he ever got the tires up to the proper temp, and if he was running the right pressures. It's tough to get race rubber warm when street riding, and any tire will lowside of you push it too far. It just seems like the tires were just one factor out of many in that crash. The fact that he was using take-offs only muddies the picture.

Like I said, I'm not trying to h8 on your buddy, but it seems to me that the tires weren't to blame for what I see in that picture.

[tilejerky]

http://www.zinio.com/express2?issue=206338267

After reading this article I've decided to give the Dunlop GP-A's a chance. I was looking for objective info, and this article is exactly that.

I'll just run the Dunlops and adjust myself to how they feel. They are supposed to offer pretty good feedback, so I'll see if I can use that feedback to improve my riding. I figure it can only make me a better rider to try out different tires (as long as I don't crash!).

I'm still interested in any feedback from people that have used these tires, so post up if you've got a minute.

[RRRR6]

i've never had dunlops on the track...

but...

I only race supercorsa pro's and they're amazing.

the diablo III is street tire but a capable track day tire. the side compounds are pretty sticky and wear is good.

I recommend wearing out your dunlops and then strictly running supercorsa pros...imho and many many others...they're the best.

have fun....i don't think you have to worry about temperature. all of those tires are designed to work well at high high temps.

[Mmelmann]

Originally Posted by tilejerky

Not to pile on your buddy that crashed, but what was he doing running so fast on public streets? He's carrying so much lean angle that he's inviting a lowside.

I kind of wonder if he ever got the tires up to the proper temp, and if he was running the right pressures. It's tough to get race rubber warm when street riding, and any tire will lowside of you push it too far. It just seems like the tires were just one factor out of many in that crash. The fact that he was using take-offs only muddies the picture.

Like I said, I'm not trying to h8 on your buddy, but it seems to me that the tires weren't to blame for what I see in that picture.

He's not really a buddy of mine... more like an acquaintance. And that road... it's known as the infamous Palomar Mountain tight side road. It will roast street rubber if you are an experienced rider and want to play. I've never seen a road like it ever before... it attracts riders from all over southern california and 98% of the riders there wear full leathers and half of those riders run full race compound tires.


I miss the hell out of that place. Watch this video (it's made by the guy that crashed and the silver GSXR-1000 is the same one in the pic I showed you guys) BTW, both guys are in their mid 40's.

Palomar Mountain Disturbed

BTW, both of these guys swear by the D209's. It's a popular tire for the fast guys of the mountain. I hated to ride on street rubber up there... they make for a greasy time.

[gsxr_fan2003]

i love palomar mtn...yeah just cruising it will make your pilot powers look like trackday tires...well sorta...they will chunk though

[tilejerky]

Originally Posted by Mmelmann

Palomar Mountain Disturbed

Nice video. Looks like a great place to ride.

[GSXR RACER MIKE]

Here's one of my classic long responses, but it has a point.

Back in the 90's one of the motorcycle manufacturers for the GP bikes (in the race series that is now called MotoGP) decided it would try and build a GP bike that had the majority of it's weight as low as possible on the bike to improve handling. Once they built the bike they had it test ridden and found out it's handling was terrible, almost to the point of being dangerous. Investigation into why this bike handled so bad revealed that a commonly held belief about motorcycles was not correct, that belief was that a motorcycle pivoted at the contact point where the tires meet the ground. Instead what they found was that bikes actually pivot around a central mass point located more toward the center of the bike, with that knowledge they then started focusing on not only centralizing the mass of the bike, but also finding where the optimal central mass should be located. After alot of R&D over the last decade or so the motorcycle manufacturers have come to the point where sportbikes now have incredible handling. Take a look sometime at articles about new sportbikes and you'll probably eventually find a statement saying something about "improved mass centralization".

Sportbikes (especially the latest models) are a collection of variables coming together to create a masterpiece of power and handling, all of those specific variables could be compared to a symphony and all it's individual instruments coming together to create something beautiful. I've used this symphony example for several things before, but a favorite is concerning engine modifications. Late model sportbike engines are truely a symphony in action, so often attempting to improve a masterpiece results in a loss of the quality of what you already had, you could actually end up with something that is not better than the original (and possibly worse). I have seen so many times in my life where someone modified only 1 or 2 things on the bike seeking a performance gain, then actually hurt the performance of the bike because they didn't do ALL the modifications that are needed to truely take advantage of the mod's they did do. In those cases they only had a few of the instruments playing the music, not the whole symphony. Handling of a motorcycle is very similar, just doing 1 or 2 things individually most likely will only produce OK results if you get lucky, but often times it can backfire and make your handling worse.

A bikes 'set-up' is comprised of numerous things including: suspension springs and valving, wheelbase length, angle of the forks and swingarm, mass centralization (which includes ride height), gearing, and of course tires. Some people are obsessed with 1 or 2 aspects of bike set-up and will let you know just how important that thing is to your bikes handling, one of those is suspension sag settings. While sag really is a variable in bike set-up, it's more of a tool to see if you have the correct springs on the bike for you, if you do then it can be somewhat useful in some fine tuning. Others will preach that tires are where it's at, and again, tires are truely important but greatly mis-understood by many. Since this is the focus of this thread I will describe it's potential effects on the bikes handling.

Tires have different profiles (or shapes) between not only manufacturers, but even models within a brand. Further more tires can have widely varied construction techniques resulting in different handling characteristics and requiring different things to work properly. For example the Dunlop DOT race tires generally run somewhere around the low 30 psi range, Michilens use about 2/3rds that much pressure in their comparable tire. The reason for this is because based on the construction of the tire it may need more or less 'support' from the air to develop the desired tire profile/shape while cornering. Having too much air will cause the tire to be more 'round' in shape and not allow it to flatten out somewhat in the turns like it should to create a larger contact patch of rubber meeting the track, too little air pressure and the tire will be mushy in the turns and feel like your riding on Jello which is a bad feeling that doesn't breed confidence. Not only can incorrect air pressure cause a bike to handle poorly, but switching to a different model tire can have negative results from the new tires profile being different as compared to the original one. Some racers will actually measure the outside circumference of tires when they switch models so they can adjust the ride height on their bike to compensate for the change. A taller tire will raise the rear of the bike which will steepen the angle of the forks on the bike and potentially make it want to turn quicker, a shorter rear tire does the opposite and will generally cause more of a change in the bike not wanting to turn as well. On top of that, where you adjust your rear wheel in it's travel at the axle will raise or lower the bike causing handling changes as well. Some people try and compensate by raising or lowering the forks in the triple clamps, but this changes the center of mass of your bike at the same time it's changing your fork angles, so it can actually backfire unless your bike already benefits by that move. These are just a few variables from a tire change only, throw more changes into the mix at the same time, like different gearing, and you can potentially screw up your bikes handling if you don't know what your doing.

The only accurate way to test tires is to have a Laser Co-ordinate Machine readout your bikes 'set-up' with each tire mounted on it and tell you what you need to change to get the bike to it's best performing set-up. The positions you need to have the bikes key components at are already known by the manufacturers to obtain the best handling in a racing condition. With the Laser they can have you adjust the bike so even with tires of different profiles and circumferences you can get to the best set-up position. What so often happens is people switch to a different tire and say it sucks really bad, when in reality there are many other racers using those same tires and having great success with them. The reason for this is almost always set-up of their bike, their bike was probably set-up closer to optimum with the original tires circumference, then they switched to a tire that was different in size (though possibly labeled as the same size) and it made the bike handle poorly due to that, not the tire itself. This is where bad info comes from, when someone who made no changes to their bikes geometry has a bad experience with a certain tire. Another thing to notice is that many times certain bikes handle better with certain tires, that's because most people don't change their bikes set-up and certain tires are just closer to working with the original factory set-up. I personally have always run the Dunlop DOT race tires and had only great success with them, yet others complain so much about them (most likely due to the set-up of their bike). It's very possible that If I used the same tires as someone who is using a different brand on a different type of bike (with great success) that I may have bad handling from those same tires due to my bikes set-up (depends if the tire is taller or shorter as too it's effects).

Your going to be riding a different bike, at a track you've never ridden, on tires you've never used before - sounds interesting. Changing the tires to something you are already familiar with may not bring the results your looking for due to it being on a completely different bike that may be set-up better for the tires that are on it. If the owner of the bike says it handles well with the tires on it currently then I would probably leave it alone, no matter what brand they are. I personally really like the DOT race tires that Dunlop makes, I have used them from 30 degrees to over 100 degrees without any problems. But as with any new tire situation (especially on a new bike and track as well) TAKE IT EASY! Have a blast!

[tilejerky]

Mike, thanks for the feedback. While your approach isn't exactly what I was looking for, it makes a lot of sense, and tends to put the tire argument somewhat into perspective.

My biggest concern was how the tires behave when pushed, like what they feel like, and if they'll give me warning. Basically, I'm afraid to lose the front, and was looking for behavioral characteristics of the tires that I could look out for (or feel for).

From what I've read the 208 GP-A's do give a lot of feedback, which is why so many racers like them. I've been told many times that I'm a smooth rider, so I'm hoping that by gradually working up to my top speed that I'll be able to feel what the tires are doing, and be receptive to any feedback that they're giving. I know that I realistically don't have the skill to push these tires past what they're capable of, but that won't save me if I do something dumb (which I usually don't).

Anyway, Mike, if you tell me that you've used these tires at over 100 degrees, that's enough reassurance for me. I had finally decided to use these tires anyway, but your post makes me feel a little better about it. Once I get the sag set and some rough baseline damping settings established I should have a pretty good foundation to work from.

It seems that tire pressures should be something like 31/31 or so. Any advice here?