Dunlop Compound names for slicks

Be honest Derek, most of what you say results in blank stares...

 

Pretty much

 

I’m going to generalize things here to simplify things. Tires have a bunch of different petroleum-based chemicals in them. The important ones for the tread compound are resin for grip, carbon black for durability, and silca for wet grip and to lessen rolling resistance.

Slick or DOT compound tires usually have zero or just a tiny bit of silica. Resin when cold is firm but when hot it’s soft, and think of resin as the “glue” for grip. Carbon black helps with longevity, resists abrasion and helps the tire be less temperature sensitive. And if you’re sticking your fingernail in the tire to judge it’s softness you are way off.

Every tire company has a “go to” rear compound (and front too) that works almost everywhere for most experts and novices so the best place to start is with your tire vendor for answers. And the worst thing you can do is buy race tires from the interwebs without the knowledge of what works best for the track/conditions/temps/and your riding level. FYI it will get easier with time.

 

A very helpful explanation. Tires are weird at times. I worked briefly with MotoGP Bridgestones and they were so unbelievably hard and oily when cold, but so fantastic when hot. Really hot. The engineers were very coy about why, but obviously chemistry was in play.

Dunlop’s are relatively easy to understand by comparison. All of them have a certain level of grip for 4-8 laps, drop off, plateau, then have to be managed. That last part is where you make decisions on race use.

 

Are any of the manufacturers using the same compound over different carcass construction to affect grip and longevity? Or is that no longer in practice?

 

Yes.

 

If I understand you correctly are you asking if in a development scenario if a standard tread compound would be tested on a new carcass design? If so then yes.

 

I'll clarify - the same compound would be used in two different tires, but the tire with one layer less of carcass, for example, would be referred to as the soft tire, while the other would be a medium grip tire.

 

I thought it was the other way around? Softer when cooler otherwise they overheat and get greasy. Hard compound in the cold seems like you wouldn't ever get heat into it. Higher pressure in the heat and lower pressure in the cold too for the same reasons.

 

Ive found for a 600/675 the 2662 front and 0455 rear works really well. Ive tried softer rears and cant extract any noticable performance out of them vs the 0455. All that happens is i get a really nasty tear especially on the softer rear.

 

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It's counterintuitive, but in cooler temps you generally use a harder compound. The softer compound will run too cool and will tear. Unless, as @stangmx13 says, you start out on warmers, adjust pressure down so that the tire will run hotter, and actually put more force into the tire to keep it hot.

 

The compound doesnt really affect heat generation much, in my experience. The harder compounds are much more resistant to tearing when not at ideal temp. So id much rather ride a Medium in freezing cold temps than an ExSoft so I can get more than 6 laps out of a brand new tire.

Pressure for the conditions is really dependent on your pace and how much you stress the tire. I'm fast enough where I tend to aim for a specific target pressure. For ex, 24psi rear off the track. So in cold conditions, I may run 22-23psi off the warmers. In hot conditions, ill run 19-21psi off the warmers. A slower rider that cant get enough heat for any pressure increase will probably do the opposite. They can run 22-23psi in hot conditions because they have some heat and are close to 24psi off the track. But in cold, they are struggling for temps and need to go lower to force the rubber to heat up.

 

The tearing on the rear can be so many things- rear spring and shock settings, track temps, pressures, and riding style all contribute. You will often find two riders on identical bikes with similar lap times, one will tear the tire and one won't.

If your spring is "right" (whatever that means), you can try adding a little pressure and speeding up the rebound (less rebound damping) to slow the tearing. However, once they tear enough, they will continue tearing.

I'm no tire expert, this is just what has worked for me. I usually start out with a little higher rear pressure than some of the faster guys around me. If the tire looks good, I'll drop a little pressure as the day goes on and I start pushing the tire harder.

 

I have a good relationship with my dunlop dealer and he is always at the track with i am. We played with pressures and etc on yhe softs and saw no improvement. On nthe same settings and lap times i get zero tear on the 455.

 

My head is spinning. So the whole deal about "hard" tires having less "grip" than "soft" is actually not even a thing?

I'm gonna dumb it down for myself here if someone wants to spoon feed me...

If it's 90+ degrees out and I'm upper A pace, what Dunlop do I use (assuming soft)

If it's 60-80 degrees out, etc etc, what Dunlop do I use (assuming hard)

I ask for this dumbed down version because I read you can adjust PSI to compensate so it doesn't matter...now I'm lost.

 

7455 both front and rear is a good start, I think. Then adjust accordingly to need and developed feel.

 

I have these options

120/70:
01.29
26.62
74.55

180/60:
01.97
00.97
01.29
04.55
05.85

I saw Gino I think it was say the 2662 is the best front for all the variables of available grip and longevity, since the 7455 isn't available here to me, I'm thinking 5.85 for the rear.

So my combo is 26.62 and 05.85 for the rest of the summer months. I've never really used a Dunlop the way it should be used. I keep finding Pirellis; as much as I like them, the stiff carcass of the Dunlop makes it feel as if I know where I am more so than the Pirelli, so this is the first time I'll be doing my best to "go fast" on Dunlops to see how it is.

 

Fascinating. I alsways heard that you lower the pressure in the cold to get the carcass to flex more and generate heat to get up to target pressure. Is this just a dunlop thing or a general rule (because I'm running pirelli and not sure it applies). As a backmarker I usually just run soft in the front for extra grip (whether real or imagined), and med in the rear as a catch all for temp, ability, and surface.

 

Hard compounds do have less grip than Soft compounds in ideal conditions. However, it may take a good/fast rider to notice or use the extra grip. And it must be in ideal conditions for that compound. A Medium rear will likely have more grip than an ExSoft on a cold abrasive track after 2-3 laps.

There is no rule of thumb for temps and compounds. Every track and each day are different. Track temp is actually more important than ambient temp. A bright sunny 70F day may have a higher track temp them than a cloud 90F day, which can allow you to use softer compounds.

If I had to blindly pick compounds to run at a trackday on an unknown track in unknown conditions, itd be 2662 front / 0455 rear. (0455 is the new 7455)

 

The "reduce pressure to generate heat to get up to target pressure" part hasn't applied for me in a while. Its a losing battle. Usually the increase in pressure rise is less than the air I took out. For ex: Ill get a 2psi rise with 21psi on the warmers. Then ill get a 2.3psi rise with 20psi (warmers). In the end, if I wanted to get to 24psi on the track I should have added pressure.

Theres no way I can know if this applies to you and Pirellis. You should just try it yourself. For the 3rd and 4th session of a trackday, try this. Push on your in lap and get a friend to measure your pressure at the hot pit wall. Its best to measure there because rolling around in the pits can suck heat fast. Then let the tires stabilize to warmer temp, change the pressure, and measure at the track wall again. You'll know right away if reducing warmer pressure actually increases on track pressure.