305 rear tires???

[Norm Peterson]

At least within SCCA there are guidelines for the distance from the course line to fixed objects. But even so, if the driver forgets "in a spin, both feet in" there's no telling what might follow.

Or to whom. A few years ago, I watched a just-out-of-the-trophies National-level driver run a Corvette over a low curb after going through the finish timing light.

Somewhat more recently, I saw a small FWD sedan end up on its roof toward the end of a slalom.

Which brings it around to there being a damn good reason for wearing helmets at speeds ranging from 20 mph to 60 or a bit more. I cringe when I see some of the "Pro-Touring"-oriented autocrosses where drivers (sometimes with helmetless passengers as well) aren't wearing them. I'd wear mine anyway. Or request an event refund and leave if any attempt to discourage me from doing so was made.


To Chevy's tire & wheel choice - it's probably getting close to the edge of corporate standards on handling, which will be at least a little more conservative than what an experienced autocrosser or track day enthusiast would still be comfortable with. Chevy has to tune a car's handling with the idea that there will be several thousand drivers, all of unknown skill. People like So Cal, Brian, myself (and a couple others in this thread so far) really only have to tune for one . . .



Norm

[white1LE]

Originally Posted by CrystalRedTintcoat

Synner, maybe another view is this video from hookedondriving.com. I posted this above in reply to So Cal Camaro. He raises a good point. Most stock cars should only be driving 7/10ths. A car modified for track can be driven 10/10ths and even 11/10ths (whatever the heck he meant by that). Anyway, this thread has gotten blown out of proportion a bit. If someone has the dough to roll his own 10/10ths car, then "Good on him" as the Kiwi's say. And if someone wants to be a 7/10th driver then "Good on him" too.

Maybe, just maybe, what's been lost in this thread is a difference of the user. Some people may be 7/10ths users and some may be 10/10ths uses. Neither are wrong. Just different.

http://www.youtube.com/embed/ut3t2is-Gt4

Well said!!!!

[Norm Peterson]

Originally Posted by CrystalRedTintcoat

Maybe, just maybe, what's been lost in this thread is a difference of the user. Some people may be 7/10ths users and some may be 10/10ths uses. Neither are wrong. Just different.

http://www.youtube.com/embed/ut3t2is-Gt4

User difference indeed.

Of course, once you've been at or above 7/10ths enough times you might have a harder time understanding why anybody would take a car specifically intended for the "2%-ers" - arguably better than 7/10ths level folks - and modify in the 6/10ths direction.


Norm

[2cnd chance]

Originally Posted by Norm Peterson

User difference indeed.

Of course, once you've been at or above 7/10ths enough times you might have a harder time understanding why anybody would take a car specifically intended for the "2%-ers" - arguably better than 7/10ths level folks - and modify in the 6/10ths direction.


Norm

Agreed.

[white1LE]

Well, to each his own. If someone buys one strictly for getting groceries, so be it. Even put snow tires on and drive it all winter long. Makes no difference. The important thing is to modify it and drive it the way you want to best fit your personal taste. Just enjoy every mile and keep it between the lines!

[JusticePete]

Originally Posted by Mgizzle

The reason it is not square on the zl1 is because it has torque everywhere, all the time, and putting anything more than 285 in the front will be undrivable steering wise.

No sir. Putting a larger front tire on the ZL1 will improve the way it drives. All 5th Gens are nose heavy and understeer badly when driven hard. One of the biggest changes to the ZL1 was to add a 28mm rear sway bar that mounts outboard of the struts to reduce understeer. It does, but the larger rear than front wheels still result in understeer when driven hard.

It is interesting that on the 1LE the front and rear tire sizes are the same, but the rear wheel is wider. That makes the 1lE an almost square tire and wheel setup to make the car more neutral with less understeer. That wheel and tire setup worked so well that they made the front sway bar larger to induce more understeer.

From and OEM perspective understeer is safer. Understeer is not more desirable. Understeer is safer becuase most drivers will lift or brake when a car starts to slide. In an understeer car with ABS slowing down or hitting the brake will help. In an oversteer car the same reactions will guarantee a spin.

Back to the ZL1. We ran ZL1 spec 305/35/20s on our L/28 OPTIMA Camaro.



We had a bit of bad racing luck at the Invitational following SEMA. The drive shaft coupler failed on our first hot lap. From a standing start on our warm-up lap we posted the 5th Fastest Time of the Day -- from a standing start on cold tires. This isn't really news. We posted the 2nd Fastest Time of the Day at the 2009 OPTIMA 1 second behind a 1965 full race Cobra with a 750 HP NASCAR motor.



Our 2009 entry was on Forgeline 19x10.5s with 305/30/19s all around. Hands down the fastest and best driving 5th Gens run on a square whee and tire setup.

[Mgizzle]

Nice car and some nice racing. So you ran zl1 spec 305s all around and were how much quicker than the 285 fronts?

Have you tried lower front higher rear pressures to get rid of the under steer?

[JusticePete]

Originally Posted by Mgizzle

Nice car and some nice racing. So you ran zl1 spec 305s all around and were how much quicker than the 285 fronts?

Have you tried lower front higher rear pressures to get rid of the under steer?

Tire pressures and much more. We see sustained 1.3G+ steady state turns. We have considered going to 18's and running 315s. With the weight and power (acceleration and braking) we can't get enough rubber under the car front and rear. The Pro-Touring cars we run against are running HUGE rubber.



We ran ZL1 lap times at Gingerman back in 2009. Our current lap times are 8 seconds faster. This is a result of continuous suspension development, LPE NA 608 RWHP (up from 560 with a blower) and a light weight full race clutch. We have the right formula. Had the coupler not failed on track we feel we would have been 1st at the OUSCI. That and $2.50 will get you a cup of coffee at Starbucks.

This is the index to Pedders Book of 5th Gen.

Pedders 2010 Chevrolet Camaro Suspension Evaluation

Foundational 5th Gen Required Upgrades

Lowering Coils and Coilovers

Trouble Free, OEM Quiet V6 Lowering

Sway Bars

Suspension Bushes

ZL1 / CTS-V Brake Upgrade for the SS

Wheels and Tires

Bush Timing, Alignment and Torque Specs

Pedders USA Camaro 2.0

Lingenfelter L/28 Tech

5th Gen Wheel Hop and Drag Race Setup

Thermal Management

Running Changes Made to the 5th Gen by Chevrolet

Public Track Test #1

Public Track Test #2 Camaro vs. Mustang Supercar Shootout

[Synner]

2.50? Try 7.50

[Teedger]

Keeping the neutral set up on the 1LE in theme... What are the advantages & disadvantages of putting 305s on all 4 wheels instead of the stock 285s. Is this an easy swap on a 1LE or are there other factors to take into consideration? Would the car handle better/worse or the same?

[JusticePete]

The best answer is found on the Z/28 which will deliver in 2014 on 305/30/19s. I wonder where they got that idea...

[2cnd chance]

Originally Posted by JusticePete

The best answer is found on the Z/28 which will deliver in 2014 on 305/30/19s. I wonder where they got that idea...

It was from this Pete guy if I remember correctly.

[JusticePete]

Originally Posted by 2cnd chance

It was from this Pete guy if I remember correctly.

[chuyito92]

Do any one know if it is recommended putting on rear 305 or 315s on a 2010 camaro rs? Do they fit with out any rubbing using 11" rims? No shaking or vibrating when driving car? Or any problems while driving? All comments Are appreciated