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Another R888 question re load

 
Old 10-31-2018, 12:59 AM
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Another R888 question re load

I was just getting excited to spec out some wider wheels and tires after last weekend track day and was thinking of 255 R888s in front and 275s in back, as many have done and have posted about, but have since learned the R888 is discontinued and no one that I can readily find online has em. The trouble is the R888 255 had a load of 94, but the replacement R88R 255 shows as 90...so correct me if I'm wrong but that load rating is too low for the car? Assuming I'm limited to 255/275 based on the wheels I have my eye on, and my desire to play around with an R-comp, suggestions or ideas? Reviews of the NT01 didn't seem super positive, Sport Cup 2s come only in one width down, and haven't seen anyone here run/comment on Federal 595RS-RRs. They are also 94s and super cheap and pushed by a local track day organizer. Anyways, yes another tire thread, but hey, at least it's not an oil thread...
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Old 10-31-2018, 11:17 AM
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Yes, the load rating is too low, and moreover all R-comps like hot pressures of around 34-36 psi which is also too low for the weight of the car. I don't know what tires BLKROKT and Clark Kent here use, but the couple of times a year I put the C63 on the track to stretch its legs I now do on the (street) Michelin PS4Ss.

Toyo and Nitto are the same company and the rubber compounds between the R888s and NT01s are the same. The big issue is the weight of the car, for which you'll always end up running higher pressures than optimal for *ANY* R-comp on the market or you risk cutting right through the sidewall and a blowout. If you have the right rim sizes, the only other tire I'd now consider would be the Dunlop Sport Maxx Race (MO) or whatever the tires that Merc put on the C63 BS from the factory are. The sidewalls and beads on those (the MO variant only) would be reinforced for the weight of the car and the treadwear is something like 80, so at least on paper that puts them on par with any other R-comp.

P.S. PSC2s and P-Zero Corsas may be another option, but I don't see a 275 rear in any of them. The 255 fronts definitely have the right load rating in all three (96Y).

Last edited by Diabolis; 10-31-2018 at 11:27 AM.
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Old 10-31-2018, 11:41 AM
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Originally Posted by Diabolis View Post
Yes, the load rating is too low, and moreover all R-comps like hot pressures of around 34-36 psi which is also too low for the weight of the car. I don't know what tires BLKROKT and Clark Kent here use, but the couple of times a year I put the C63 on the track to stretch its legs I now do on the (street) Michelin PS4Ss.

Toyo and Nitto are the same company and the rubber compounds between the R888s and NT01s are the same. The big issue is the weight of the car, for which you'll always end up running higher pressures than optimal for *ANY* R-comp on the market or you risk cutting right through the sidewall and a blowout. If you have the right rim sizes, the only other tire I'd now consider would be the Dunlop Sport Maxx Race (MO) or whatever the tires that Merc put on the C63 BS from the factory are. The sidewalls and beads on those (the MO variant only) would be reinforced for the weight of the car and the treadwear is something like 80, so at least on paper that puts them on par with any other R-comp.

P.S. PSC2s and P-Zero Corsas may be another option, but I don't see a 275 rear in any of them. The 255 fronts definitely have the right load rating in all three (96Y).
I know BLKROKT uses PSC2s but not sure on the sizes. I know he has some rear fender mods to run wider tires. He swears by them, and plenty of people seem to like them.
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Old 10-31-2018, 12:01 PM
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Just up the psi a bit.

It sometimes gives a rating on tirerack that it shouldn't go under X psi to maintain load.
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Old 10-31-2018, 12:05 PM
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Originally Posted by Adi-Benz View Post
Just up the psi a bit.

It sometimes gives a rating on tirerack that it shouldn't go under X psi to maintain load.
I don't knoooow. If diabolis says the tire won't work, I would listen. People have gone against his advice on tires before and it did not go well...
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Old 10-31-2018, 12:20 PM
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Oops, my bad, I didn't specify one key fact making all this more complicated. I'm talking about 18" wheels, not 19s. 18x9 fronts, 18x9.5 rears. Per Diabolis' many cautionary posts on proper wheel width, I believe I can run 255s on 9" and 275 on 9.5s, at the max. I don't really want/need to go wider and the 18" wheel is where I'm at re project costs. I'm not finding Sport Cups in those sizes, but 245/265. Anyways, appreciate the ongoing feedback on what could work and support the car!
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Old 10-31-2018, 01:05 PM
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The PCS2s are a "nice" medium (180 treadwear - not quite an R-comp that's sticky enough that you'll end up cutting the sidewall) if you properly support and inflate them, which on a 4,000 lbs car would be at the upper end of the approved rim width. For a 245 & 265 combo I would use at least 9" and 10" wide rims respectively, and have the hot pressures near 39-40 psi. Those pressures are higher than ideal, but you really don't have any choice but to run them that high unless you gut the car and shed 800-1,000 lbs.
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Old 10-31-2018, 01:23 PM
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Originally Posted by chrisridebike8 View Post
I don't knoooow. If diabolis says the tire won't work, I would listen. People have gone against his advice on tires before and it did not go well...
Oh definitely, I'm not saying don't yield his advice, but this is a relatively common thing with lower profile tires so as long as you follow proper specs and not you should be fine; that said, it's even better to not have to worry about it.

Else you could be blowing out and other bad stuff.
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Old 11-03-2018, 09:28 AM
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Ran into these new yokos. Different from AD08s. They look promising for widths and loads.
https://www.tirerack.com/tires/tires...52XL&tab=Sizes
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Old 11-03-2018, 12:05 PM
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Originally Posted by chrisridebike8 View Post
I know BLKROKT uses PSC2s but not sure on the sizes. I know he has some rear fender mods to run wider tires. He swears by them, and plenty of people seem to like them.
My MPSC2’s are 255/35 F and 295/30 R. On the fronts I try to keep hot pressures around 46psi on track because my rim is too narrow at 8.5”. Car definitely understeers more esp under heavy braking where the front is already overbraked for tires at that pressure, but that seems to be what eliminates the sidewall issues I was having and works best for me however YMMV. In the rear I like them at around 41/42psi hot. It’s important to note that my pyrometer is useless because Michelin uses multiple tread compounds across the width of the MPSC2, which heat at different rates. Really have to pay attention to how the car feels in order to dial them in. Anyway, as Chris said I love these tires for our cars. They grip about 90% as well as the other rcomps I’ve tried, but the new 180 treadwear rated compound makes them last noticeably longer, especially when running them hard on hot summer days. I got through this whole season on one set (barely) which is really unusual. My suspension and underbody changes are really working right now, and maybe that has something to do with it. Think that getting them from TireRack already heat cycled made a big difference in wear as well. The sidewalls are stiffer than other rcomps I’ve tried, and I find them to be more predictable too. Don’t see myself running anything else unless I jump to full slicks (which present their own set of challenges to find a 19” that can handle the weight)

For whatever it’s worth because I saw it mentioned, I also ran the Dunlop Sport Maxx Race for a few events last year. Decent tire but degraded very quickly and got super greasy on hot days. Maybe they’re better shaved, I don’t know. And I folded a front sidewall running them at just a little too low pressure on a hot day in July. Not rolled, folded. That was scary and the end of the experiment with those tires.

At the end of the day, you absolutely have to go with a tire that’s weight-rated as high as possible. Even higher than the M0-spec if possible. That’s got to be your first filter, then width, diameter, compound, etc. And you should determine tire width by the maximum suggested rim width in the range for the size. These cars throw around a ton of weight on track and there just aren’t many tires that can handle the lateral loads, and you’ll be compromised if you try to squeeze a wide tire on a narrow rim.

Last edited by BLKROKT; 11-03-2018 at 01:45 PM.
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Old 11-03-2018, 09:54 PM
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Nice thanks man. Well, given my predicted rim widths would be 9 front and 9.5 tears based on what Iím shopping, perhaps the best thing to do based on feedback is just run the sport cups in 255 front and 265 rears since they donít have a 275.

Maybe slap on some lightweight girodisc two piece rear rotors for good measure.
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Old 11-04-2018, 06:49 AM
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About Federal 595 RR:
I was trying to put together a set of track day wheels for my Subaru, so looked into those. But the reality is that I would have used them as summer wheels as well.
So I've read some reviews, trying to figure what to expect.
Track day they're good, but the noise on the road seems to be such that posters that are used to noisy tires described some sort of constant hum.
The second thing is that the behavior in rain seemed to be crap.
The third things is that the predecessor of the RR had some kind of "Thread splicing delamination", where more or less tha thread starts to separate, but because you're seasoned pilot, you know how much longer you can drive it before you're in danger. Maybe the RR will show the same.
I'm not a seasoned pilot and don't like to gamble with the life of the tire thread.
I'm guessing that for the money, as a pilot you buy two sets of federal vs one michelin and when the time comes, you dump the first set, install the second (or have two sets of race day wheels) and win the race because you have fresher tires, for the same money. As a result, you think the Federals are a great option.
This logic doesn't apply well to me, so I passed on the RR's.
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Old 11-05-2018, 01:12 PM
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Originally Posted by Crya View Post
Ran into these new yokos. Different from AD08s. They look promising for widths and loads.
https://www.tirerack.com/tires/tires...52XL&tab=Sizes
If you're thinking about a 200 treadwear tire, look into Nitto NT05s (not the 05Rs - those are drag radials). Inherited a fresh set when I got the 'vette and they were surprisingly decent (I am only talking about dry grip levels at the track). I'd put them up against anything this side of a PSC2s... Bridgestone RE71Rs, Hankook RS4s and the like.
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