[seanblurr]

Putting in longer studs with a 5mm spacers is not needed in my personal opinion. I don’t think I would use anything thicker than that though with the stock studs.

[RUQWIKR]

Originally Posted by seanblurr

Putting in longer studs with a 5mm spacers is not needed in my personal opinion. I don’t think I would use anything thicker than that though with the stock studs.

That's only around 9mm engagement. Have not looked, but does SCCA require 14mm on M14 stud? From my drag racing days, NHRA's rule states: "The thread engagement on all wheel studs to the lug nut, or lug bolts to wheel hubs, must be equivalent to or greater than the diameter of the stud/bolt."

[RXtacy]

Originally Posted by RUQWIKR

That's only around 9mm engagement. Have not looked, but does SCCA require 14mm on M14 stud? From my drag racing days, NHRA's rule states: "The thread engagement on all wheel studs to the lug nut, or lug bolts to wheel hubs, must be equivalent to or greater than the diameter of the stud/bolt."

FWIW the height of a standard M14 hex nut is only 11mm (i.e. 11mm thread engagement max).

[RUQWIKR]

Originally Posted by RXtacy

FWIW the height of a standard M14 hex nut is only 11mm (i.e. 11mm thread engagement max).

The lugs I am using allow the full engagement. At 140ft-lbs, I am seeing right at or above 14mm engagement with stock wheels (no spacer).

[RXtacy]

Originally Posted by RUQWIKR

The lugs I am using allow the full engagement. At 140ft-lbs, I am seeing right at or above 14mm engagement with stock wheels (no spacer).

That's good, never hurts to have more engagement. I was simply showing a point of reference that a standard class 10.9 M14 hex nut (recommended torque 160 ft-lbs) only needs 11 mm of thread engagement.

[FNxR3DNECK]

Originally Posted by RUQWIKR

Will do later on the pics. Rims are off the car again as, for now, I'm just going to race o. The MMR sizes you are getting will be SCCA AS legal where the A1Z's I have won't be. I've got a set of the 19x10.5 (+14OS) MMR716's on pre-order to help with the poke out on the front with our narrow fenders.

That's exactly what I plan to use them for! This is going to be my setup for AS next year with 305/30/19 RE71Rs! Should save at least 8lbs on each corner and the wheels cost me less than $1200!!! Could have gone with a lighter setup but couldn't beat the deal on these!

[glamcem]

adding longer studs on Gen 6 Camaro is a lot easier than the Gen 5 Camaro as grinding/modification to the hub is no longer required, just an FYI

[rfm4000]

wow the tires are surprisingly cheap. Im def getting 19s just for track setup.

[RUQWIKR]

Originally Posted by rfm4000

wow the tires are surprisingly cheap. Im def getting 19s just for track setup.

...and surprisingly expensive based on how quickly they wear. Great grip for as expected, but I am not sure they are worth it for how quickly they will wear. Your own pocketbook will determine. Most R-compound tires are reduced tread depth, but, at least the RE71R are 8/32" not 3 to 4/32". The NT01 is 6/32".

In another thread, GLACEM wrote:

How was the overall balance of the car compared to OEM wheel/tire setup? BETTER AND MORE STABLE
Any increased mid corner push/understeer? DON'T THINK SO
Do you remember approximately how many sessions they lasted? 600 HIGHWAY MILES AND 280 MILES ON TRACK: 8 X 20 MINUTES ON 3.1-MILE TRACK PLUS 6 X 20 MINUTES ON 1.3-MILE TRACK. CORDED RIGHT FRONT OUTER, CHANGED FRONTS BUT REARS WILL MAKE IT ONE MORE TRACK DAY, MAYBE TWO
Ambient temps? Longer or shorter sessions ? 82-86F / 105-109F TRACK TEMP MAX, 20-MINUTE SESSIONS
What were the starting and hot tire pressures? SEE BELOW
Lap time delta between G3s, G3Rs and/or RE71R? SEE BELOW

Sorry for asking so many questions I have been seriously considering these tires and am a bit surprised that they didn't last more than 3 events considering the size and the load rating on them.

For the reference, my NT01s after 3 events still look new (305/325-30-19) especially the rears. Fronts are slightly losing the tread but I believe I can still get a few more events out of them and they wear evenly. They're about 1-1.5 second faster at both tracks.


To try to answer his questions, let’s compare two laps during two events at Motorsports Ranch – Cresson (Texas) on the 3.1-mile full course, run Counter Clockwise. Elevation changes, decent straights, very hard on RF tires. Car is stock other than factory wicker bill and GM Performance air box (stock throttle body duct). Both runs with ~half tank of fuel with 200+# driver. Bright and sunny, and one side of the car was always in the sun when pitted, which contributed to differences in starting tire temp (from TPMS, not tread temp). I did not take tread temps with my pyrometer.

The tires were rotated side-to-side after each day, but, for the three days, the two tires that started on right spent two days there and one on the left side of the car.

Per HP Supplements, starting and hot pressures for both tire types:
G3: 26psi starting and 32 - 35 hot for both front and rear
G3R: 28psi starting for both front and rear but hot pressures 35 – 37 front and 37 – 39 rear


9/9: G3’s, 82F ambient, 105F track, 2:32.22, Avg Speed 72.51mph, 1.35g max (1.44 on a slightly slower lap), Time on Accelerator 53.1%, Time on Brake 18.6%.

Starting and finishing tire pressures plus temperatures:
LF 29.6 psi / 36.5 psi (5.9 delta), 100F / 183F (83 delta)
RF 29.6 / 37.7 (8.1), 93 / 196 (103)
LR 29.8 / 36.5 (6.7), 97 / 163 (66)
RR 29.6 / 37.1 (7.5), 93 / 174 (81)

10/7: G3R’s, 86F ambient, 109F track, 2:28.44, Avg Speed 74.84mph, 1.40g max, Time on Accelerator 55.4%, Time on Brake 17.0%.

Starting and finishing tire pressures plus temperatures:
LF 30.3 psi / 38.9 psi (8.6), 100F / 183F (83)
RF 30.5 / 40.6 (10.1), 95 / 196 (101)
LR 30.2 / 38.3 (8.1), 98 / 171 (73)
RR 30.7 / 38.3 (7.6), 95 / 176 (81)

I felt faster / quicker with the G3R’s, more stable, more predictable, as would one think. The ~3.8-second improvement is a combination of the tires and more laps on the given track configuration. What % of the improvement is experience vs. tires, who knows. The G3’s have twice the Tread Wear rating and a bit more tread depth stock. I got seven track days with them at MSR-Cresson, but, all were on the 1.7 mile course which is not as hard as the 1.3 (which combined with 1.7 becomes the 3.1 configuration). So, wear is kind of comparable based on TW rating. Would be interested in what the delta improvement would be if we had regular G3's available in the same sizes as the G3R's.

As expensive as any of these tires are, as fun as 3+ seconds quicker is, is it worth twice the price based on wear? A ZL1 or ZL1 1LE would kill these tires off that much more quickly. See pics below.

[Ryephile]

3.8 second improvement with just tires despite hotter ambient temp, holy crap that's incredible. That would put them right on-par with Hoosier R7's, it seems.

Thank you for all the setup and datalogging info, that's really good to see.

[RUQWIKR]

Originally Posted by Ryephile

3.8 second improvement with just tires despite hotter ambient temp, holy crap that's incredible. That would put them right on-par with Hoosier R7's, it seems.

Thank you for all the setup and datalogging info, that's really good to see.

Like mentioned, 'x' of that is just more time with the car and the track since this is my first year going fast while turning (vs. 35 years drag racing). I think most was the tires. I have new fronts already mounted (one pic below for new G3R reference) and will see what I can get out of the rears. Here are pics of three of the four. The circled area on the left front outer shoulder is where the delamination and slight cording occurred on the RF. Front is around -2.8 camber, -1.8 rear.

That area is thinner cross-section, so, even with side-to-side rotating and negative camber, on tracks with high lateral loads to the outboard side, I'm not sure of how to keep from wearing that out without even more negative camber. Thoughts?

[Chris V]

Any pics of the grinding? Is it grinding and spacers or grinding or spacers?

[Ryephile]

10-4, thanks. Even if the tire's gave only half that time, it's still a big improvement.

It seems our 1LE's would greatly benefit from stiffer anti-roll bars to keep the dynamic camber in check. That would definitely improve the tire wear (and grip from using the whole tire instead of being on the shoulder so prominently).

[RUQWIKR]

Originally Posted by Chris V

Any pics of the grinding? Is it grinding and spacers or grinding or spacers?

No spacers, just profile ground where the rim would contact the laminated steel area. No pics, but, red circled area is where you need to grind.