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.

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.

http://sphotos-a.xx.fbcdn.net/hphoto...42717624_n.jpg

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

2.50? Try 7.50

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?

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. :wave:

:biggrin:

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

Poke around in the sections dedicated to Road Race/AutoX, Drag Racing/Launch, and Tires/Wheels. I'm sure that somebody has done it, if with a little extra care about things like offset.

Or just look at what the ZL1 wears . . . http://www.tirerack.com/tires/Select...oModClar=Coupe


Norm