Wear pattens of RA-1, R-888, and NT-01s

#1

I was flipping some R-888s today and noticed that there is a step level change in the middle of used tires.

It looks like the outside half wears down quicker than the inside half. You can really notice a “step” right in the middle R-888s.

On RA-01s, I use to get “Groove Of Doom (GOD)” which is a sort of dip wear patten about 1/3 in from the outside edge of a tire.

NT-01 seems to give me the most even wear across the surface even though I still wear out the outer edge (about 1" in from the wall) faster than the rest of the tire unless I rotate and flip often.

YMMV. It’s just something I found interesting.

P.S. - Would you still use a tire that requires a lot of weight (6 oz. total) to balance it? I’m not sure if the junk on the tire is throwing it off balance or maybe it has been flat spotted.

#2

One other thing;

R-888 side walls are stiffer than NT-01 side walls which are stiffer than RA-01s.

#3

That’s interesting - ours wear out the insides of R888 much faster. I’m sure it has to do with camber settings (we need to back ours off a bit). Tire temps on the inside are significantly higher. What camber are you running? We are -3.4 in the front…

#4

My first set has worn faster on the inside also. The tread is all curled up. I flipped them a couple weeks ago with the hope to even out the treadwear.

#5

-3.0 up front.

#6

My r888s were new and unshaved before RA weekend last Fall, and I was just looking at the tires. I definitely see more wear on the outside edge (getting into the triangle on the outside, but not on the inside).
I’m running -3.5 on front and -2.5 on rear.
I think I was also at 32psi cold… I probably could have spent another lap or two warming them up before pushing them :woohoo: , but do you think a pressure adjustment would have an effect? :unsure:

#7

Gilles wrote:

[quote]My r888s were new and unshaved before RA weekend last Fall, and I was just looking at the tires. I definitely see more wear on the outside edge (getting into the triangle on the outside, but not on the inside).
I’m running -3.5 on front and -2.5 on rear.
I think I was also at 32psi cold… I probably could have spent another lap or two warming them up before pushing them :woohoo: , but do you think a pressure adjustment would have an effect? :unsure:[/quote]

32psi cold is a lot, especially for the front. Be that as it may, I’d focus on hot pressures, not cold.

#8

I got to try out used R-888s past weekend. They were from two different sets and I don’t know how many heat cycles they had each.

The bottom line is I didn’t like them.

They bounce more over imperfections on the track rather than absorbing the bumps. They also break away more abruptly than RA-01s or NT-01s.

After spinning twice in one session, I did adjust to the tires but really had stay shy away from the limits and couldn’t really enjoy the tires.

As for the pressure, I ended up with 28 LF and 29 on other three tires. That gave me 36 at the paddock. Those pressures are similar to what I have used for NT-01.

#9

csrow wrote:

I’m wondering if this has anything to do with the way the tires felt. I don’t think your review is really worth much when you are running mismatched sets with an unknown history. All we can conlcude is that R888s with an unknown number of hitcycles that are then mismatched suck :slight_smile:

#10

Agreed. Not really a review for the front runners but as an HPDE guy who uses tires down to the cords, it wasn’t a good news to me as I won’t be purchasing any used R-888s.

YMMV.

#11

Elephant4 wrote:

[quote]csrow wrote:

I’m wondering if this has anything to do with the way the tires felt. I don’t think your review is really worth much when you are running mismatched sets with an unknown history. All we can conlcude is that R888s with an unknown number of hitcycles that are then mismatched suck :)[/quote]

That might be a little dismissive. Chi and I run worn out mismatched RA1’s all the time and even tho traction wanes after lots of heat cycles, I think that Chi and I (and most folks?) would agree that the RA1’s are still pretty predictable. What caught my attention in Chi’s post is that he didn’t say “predictable”, he said “abrupt”.

#12

I wasn’t dismissing his opinion I was just pointing out that you can’t really say you hate a tire based on some used up examples. If you are comparing used tires then that is a different matter. On that analysis I would say Hoosiers are complete crap. I would agree that the RA1 is going to be more consistent over the life and hence a good used tire. I think we can all agree that the RA1 is the better DE tire for sure.

#13

On R888s, what would you all say is an ideal hot/paddock pressure to shoot for?
36?
38?

#14

I have found 40 psi right off the track feels pretty good. We started with 30/31 left/right split at CMP this weekend. We really needed to flip the tires on the rims after 3 sessions, but no tire vendor was there. I put 6-7 sessions on a set of 3/32nds shaves and the tread is gone on the inside half. I will keep running them as practice tires to see how long it takes to cord them…

Maybe 4/32nds would be a better balance between preventing heat buildup and getting more longevity?

Is it too early to lobby for an all-out tire test for next year? I know CMP is tough on tires, but I don’t really want to put a new set in the budget for each weekend.

I have fond memories of the Hoosiers and would love to test them on the E30. But, then again, that was from a couple years ago in a lighter car with me not pushing as hard (but still at the limits of my talent).

Is it too early to lobby for legalizing “slotting” the shock towers to get more front camber out? I am as de-cambered as possible in the front and still getting bad inside wear. I think I might be ok at tracks with longer sweepers or grippier asphalt, but I don’t think the tire is rolling over enough at CMP to benefit from all the camber.

Steve D.

#15

Gilles wrote:

[quote]On R888s, what would you all say is an ideal hot/paddock pressure to shoot for?
36?
38?[/quote]

I was hoping for 40 hot at the track. So, after a cool down lap, I look for around 36 in the paddock.

#16

Chi and Steve, thanks for the psi info, but Steve, I’m kind of shocked that you are getting wear on the inside and wanting to take out camber… really? I’ve only done a handful of HPDEs in this E30… only one since my camber plates, but I still got more outside wear. Is it just CMP? or the fact that your tires are shaved?

#17

Gilles -

CMP is rough on tires. The braking zones are abrasive, which would tend to wear the inside half of a tire with positive camber.

My understanding is that people find the 888 sidewall to be stiffer than the RA1, so the tire rolls over less (so less static camber = the same dynamic camber we used to get).

The shaved/full tread condition should not affect the wear pattern. With some tires (jury’s still out on the 888, I think) shaved tires actually last longer and are preferable because they resist heat buildup, tread chunking, tread block squirm. I think I will go 4/32nds next time.

Disclaimer: I am no suspension guru. I know enough to be dangerous. That said… I don’t know why you would have outside tire wear unless you are getting a lot of bushing deflection. Is it outside wear on both ends of the car? I guess a real bad understeering condition would give strange wear on the fronts (but I don’t know if that would abuse the inside or outside edge of the tire). I don’t know what effect caster might have on tire wear unless it is set at a whacky extreme.

Steve D.

#18

The tire wear objective is even tire wear across the surface of the tire. That’s why proper camber setting requires some methodical pyrometer work. Which, of course, I’ve not done.

Given our -3.5 camber limit, tire wear on our outside edges is pretty normal I think.

Tires wear on the outside edge when your car’s body roll exceeds the tire’s camber. So if you’ve got -3deg in front and your car rolls 3.5deg, then the tire is at +0.5deg relative to the track.

Roll angle is a product of a number of things, but is primarily the interplace of the car’s center-mass with spring stiffness and swaybar stiffness. We have soft springs and a fairly high center-mass, so we have a fair amount of roll.

There’s a number of variables that create different camber conditions in the front vs. the rear.

  1. Our cars are front heavy.
  2. It’s the front tires that are pointed away from the car’s direction of travel so they have higher lat g loads.
  3. Rear tires have the additional burden of propelling the car while in the turn and that creates conflicting camber requirements. Therefore -3.0 F, -2.2 R might be a workable set up.

I wouldn’t change camber settings until first identifying what you have and comparing it to what other folks have. If you’re running -2.5F, -1.5R and you are planning on taking out camber, then you are headed in the wrong direction. You should focus instead on figuring out why the inside of your tires are wearing out. If you’re running roughly the same camber settings as other folks, you should find out what their experiencing for tire wear.