1LE Rear Tire Size

[Big C CamaroSS]

I've read through this thread and I still don't know an answer to my question.....is it "OK" to put 305/35/20 GY F1 tires on the rear of my 1LE so the tire set up mimics the ZL1?

[CamaroTom]

Originally Posted by Big C CamaroSS

I've read through this thread and I still don't know an answer to my question.....is it "OK" to put 305/35/20 GY F1 tires on the rear of my 1LE so the tire set up mimics the ZL1?

Yes, it will be perfectly fine, but at the limit your car will push more in the corners with the 305's.

[L99CAMA2011]

Originally Posted by Norm Peterson

Unless you ran this comparison on a real 1LE or on an SS that was completely updated to 1LE specs for wheels and suspension tuning, any comparison is of rather limited value.

Sure, the wider rear wheels provide a minimal understeer effect (it's a relative rear vs front slip angle thing). But the basic grip of identical front and rear tires remains essentially constant. Staggering the tire sizes on a normally aspirated car without doing anything else is a recipe for increasing understeer. Period.



"Handling" isn't exactly an absolute measure - it's partly dependent on driver preferences and driving style. Some people either want or need a little more straight line stability or cushion against oversteer than others. What I'm hearing is that you'd rather have the front end push a little more as long as it gives you a bigger cushion against too much throttle on corner exit giving you too much throttle (over)steer. That's fine that it suits you better.

Neither a 295-wide or a 305-wide tire on 11" will have as direct a feeling of response as the 285/35; relatively speaking there will be slightly less 'crisp' response to cornering or changes in conditions while cornering. This can be seen as a disadvantage. That you can add power a little sooner is the Band-Aid that tries to cover it up.

Up-sized rear tires are under-utilized for most of the corner, which probably does suit a "point and shoot/stab and steer" driving style a little better than driving styles that more smoothly add throttle, just like staggered tires or tires and wheels has been an appropriate crutch for the big power forced-induction cars. Probably turns people even more into becoming P&S/S&S drivers.


With quite a bit less power than a 1LE and somewhat less tire, it's still easy enough for me to get to where throttle steering can be felt. Mostly it's felt on tighter turns, but every once in a while I get the opportunity to run a higher speed sweeper hard enough to be on the edges of throttle steer. I find it easy enough to modulate the throttle to where I really wouldn't want more understeer getting in the way on turn-in and mid-corner.


I was up in the Norton/Foxboro/Bridgewater vicinity earlier this week on family business. That anywhere near you?


Norm

Close to me yes. But Norm I see your point and my bad for not mentioning that I have the Pfadt swaybars. You can actually run a staggered setup with these bars and still be very neutral, other bars didn't do that. Sorry for not mentioning this. But yes the BF Goodrich in the rear is tighter and yes now compared to the Pirelli 295-35-20 the 285-35-20 BF does feel a bit more understeerish, also the car doesn't rotate as well now as it did with the Pirelli. This is one reason I still left the rear softer cradle bushings in.

[L99CAMA2011]

Originally Posted by Cody6.2

I've put complete suspensions on at least three cars now and never once used tires for tuning it. In the end GM built this car to understeer and it will take more than three steps forward to make up for those five steps back. It would've made much more sense to do the same wheel tire combo all around than this set up.

"I've put complete suspensions on at least three cars now and never once used tires for tuning it." Can I ask a question. How many of you guys actually talk to race car techs instead of just being street guys. I once had a guy who raced professionally tell me how tires can make or break a car even with the most advance suspension and coilovers, I thought what the heck does tires have to do with it. Well lets see, 205-50-15 front and 195-50-15 rear on my 325e BMW E30 to kill the understeer with that inline 6 iron block worked, same size tires and rims on my 944 Porsche worked. My current SS Fe3 swaybars needs a squared setup, Pfadt ZL-1 bars don't need square setup. I've bought and sold God knows how many suspension parts, coilovers, swaybars, endlinks and guess what it was the wheels and tire option after tons of research that really bought my car to life enough said. If you think tires aren't a factor in how a car handles then automotive handling 101 is always available. You can even put a wider softer tire in front and same size firmer sidewall tire in the rear and still have tons of understeer, this was actually one test I just did 3 weeks ago with the Hankook Ventus V12 evo tires I had on the 19x9.5" rims in front. When replaced with Nitto NT05 The car is way more neutral, firmer steering and turns in way quicker even though the nittos have 1.8th of an inch narrower treadwidth compared to the Hankooks.

[2cnd chance]

Originally Posted by Big C CamaroSS

I've read through this thread and I still don't know an answer to my question.....is it "OK" to put 305/35/20 GY F1 tires on the rear of my 1LE so the tire set up mimics the ZL1?

Originally Posted by 1LEMayhem

Yes, it will be perfectly fine, but at the limit your car will push more in the corners with the 305's.

^This.
It may look better (it's only adding around a 1/2 inch in width), but it will disturb handling some.

[L99CAMA2011]

Also something that is going to shock the crap out of a lot of you guys on here, the 275-40-20 stock Pirelli vs the 285-35-20 Goodyears has only .3" less threadwidth than the 285s oh yeah hard to believe isn't it. Check out the specs. 285-35-19s check out a few different brand tires in this size and analyze the thread width (footprint) of the various brands and see how they differ even though the numbers (285-35-19) stay the same,http://www.tirerack.com/tires/tires....=yes&tab=Specs

[Cody6.2]

Originally Posted by L99CAMA2011

"I've put complete suspensions on at least three cars now and never once used tires for tuning it." Can I ask a question. How many of you guys actually talk to race car techs instead of just being street guys. I once had a guy who raced professionally tell me how tires can make or break a car even with the most advance suspension and coilovers, I thought what the heck does tires have to do with it. Well lets see, 205-50-15 front and 195-50-15 rear on my 325e BMW E30 to kill the understeer with that inline 6 iron block worked, same size tires and rims on my 944 Porsche worked. My current SS Fe3 swaybars needs a squared setup, Pfadt ZL-1 bars don't need square setup. I've bought and sold God knows how many suspension parts, coilovers, swaybars, endlinks and guess what it was the wheels and tire option after tons of research that really bought my car to life enough said. If you think tires aren't a factor in how a car handles then automotive handling 101 is always available. You can even put a wider softer tire in front and same size firmer sidewall tire in the rear and still have tons of understeer, this was actually one test I just did 3 weeks ago with the Hankook Ventus V12 evo tires I had on the 19x9.5" rims in front. When replaced with Nitto NT05 The car is way more neutral, firmer steering and turns in way quicker even though the nittos have 1.8th of an inch narrower treadwidth compared to the Hankooks.

In case you haven't notice the Camaro isn't a race car nor was it built to do what it is now. Given it's got a rigid chassis it was still designed with understeer in it just like most cars these days. Two of the five steps taken forward with the 1LE and ZL1 options were to break even. Race car tech doesn't even apply to my Corvette and it's light years ahead of a Camaro. There's a difference between endless and limited adjustments.

GM did a great job polishing a turd with even the FE4 let alone the 1LE & ZL1. But I still think tuning out undesiresble chassis traits with stretched tires out back is a bit silly.

[Norm Peterson]

Originally Posted by L99CAMA2011

Can I ask a question. How many of you guys actually talk to race car techs instead of just being street guys. I once had a guy who raced professionally tell me how tires can make or break a car even with the most advance suspension and coilovers, I thought what the heck does tires have to do with it.

At least in the past, sometimes all you had to do have done for that to make absolute sense was pay a little attention. I still remember having a clear "ah-ha . . . wow" moment shortly after fitting bias-belted tires to a car that had always had plain bias tires previously - slapping me upside the head would have been noticed only a little more strongly. It's almost too bad that that sort of opportunity is no longer reasonably available.

Originally Posted by L99CAMA2011

Also something that is going to shock the crap out of a lot of you guys on here, the 275-40-20 stock Pirelli vs the 285-35-20 Goodyears has only .3" less threadwidth than the 285s oh yeah hard to believe isn't it. Check out the specs. 285-35-19s check out a few different brand tires in this size and analyze the thread width (footprint) of the various brands and see how they differ even though the numbers (285-35-19) stay the same,http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Eagle+F1+Asy mmetric+2&partnum=835YR9F1A2XLN0&vehicleSearch=fal se&fromCompare1=yes&tab=Specs

If you look a little further, you'll even find at least one 265/40-18 claiming to have more tread width than the exact same model tire in 285/35-18 (Michelin PSS).

This kind of makes me wonder what criteria really exist for tread width claims, as the locations within the shoulder areas it "ends at" are really pretty vague. And where its importance stands relative to either nominal size or actual section dimensions.


Norm

[L99CAMA2011]

Originally Posted by Cody6.2

In case you haven't notice the Camaro isn't a race car nor was it built to do what it is now. Given it's got a rigid chassis it was still designed with understeer in it just like most cars these days. Two of the five steps taken forward with the 1LE and ZL1 options were to break even. Race car tech doesn't even apply to my Corvette and it's light years ahead of a Camaro. There's a difference between endless and limited adjustments.

GM did a great job polishing a turd with even the FE4 let alone the 1LE & ZL1. But I still think tuning out undesiresble chassis traits with stretched tires out back is a bit silly.

"But I still think tuning out undesiresble chassis traits with stretched tires out back is a bit silly. " don't get me wrong I think this idea is more than silly, from day one I thought why would any company have a tighter tire fitment in the rear where as other companies do it up front for sharper steering. Tighter rear tire fitment is a remedy for understeer. On the race tech part I am saying that methods used in the race pits can trickle down to our road cars giving us improved results. And honestly the vette still has issues, more advance than the Camaro yes but it still has a rear leaf spring suspension. And from observation a Camaro gen 5 still takes more speed into corners than the corvette this is a fact. The Camaro still has more grip than the vette. You think I would take a vette around corners the way I do my Camaro especially on wet or in winter with 29 degree temps heck no. Vettes are demand more respect on corners and more attention. Personally I like the Vette C6 more than the Camaro but there is still things the Camaro does better than the vette and I am not talking about the rear seats either. I have driven many vettes.

[L99CAMA2011]

Originally Posted by Norm Peterson

At least in the past, sometimes all you had to do have done for that to make absolute sense was pay a little attention. I still remember having a clear "ah-ha . . . wow" moment shortly after fitting bias-belted tires to a car that had always had plain bias tires previously - slapping me upside the head would have been noticed only a little more strongly. It's almost too bad that that sort of opportunity is no longer reasonably available.




If you look a little further, you'll even find at least one 265/40-18 claiming to have more tread width than the exact same model tire in 285/35-18 (Michelin PSS).

This kind of makes me wonder what criteria really exist for tread width claims, as the locations within the shoulder areas it "ends at" are really pretty vague. And where its importance stands relative to either nominal size or actual section dimensions.


Norm

That's kinda why I posted that Norm a few weeks ago I was thinking of running a tire that fits the 19x9.5 tight on the rim but wanted a wider thread width, figured that I would have to run 275s or 285s. 285s would be too loose for a front wheel. 2 weeks and researching TireRack specs from the manufacturers I realized that yes there were 265 with even more threadwidth than even 285s figured the TireRack experts could've mentioned this. I actually had to tell a few of them about this, they were shocked. Yes I could've bought that 265 tire for the front and still have more threadwidth in front that 275 or some 285s. Even the Nitto 275-35-19 NT05 is measured 9.79 from factory and with my tape measure nice huh. So much for judging tire size by the number written on the tire side wall.

[Norm Peterson]

I wish I could realistically justify some test-n-tune myself, but at $1000 or so per test just in the tires I'm afraid that that's not gonna happen. And I need a fresh set for track time since I had to repair one of my summer tires. They're still fine for street duty up to and including the occasional fairly enthusiastic 3rd gear run through stretches like the 140 to I-195 East ramp, but they absolutely do not belong on any car being used 20 minutes at a time at a still harder pace with some heavy, just-short-of-ABS braking repeatedly thrown in for good measure.

Best I can do is research, read about other peoples' experiences and thoughts (here and elsewhere), and crack open a couple of college-level tire books hoping for a little more technical insight.

The direction taken for the 1LE's tuning is intriguing, though it was probably an easier step to get there from the SS models with different width front and rear wheels than it would be starting from cars that were always fitted "square" in terms of both tires and wheels. Once the argument concerning tire rotation goes away for any reason, it stops being an objection for all of the reasons you wouldn't rotate them. After that, there is the matter of appearance, which I mostly see as defining who sits where on the spectrum from pure functionality to pure form.


Norm

[Fraxum]

Im not a track engineering expert by any means, but the 1LE works!

Supercar handling for $3,500? I bet the tires play a big part in this. My 2011 SS had a very modified suspension but the stock Pirellis. They never wore out while I had the car. Like Norm I have a practical streak.

But my 1LE even with rubbery bushings and smaller sway bars would out handle my 2011 SS. I think Norm put his finger on it. Balance.

[JusticePete]

Originally Posted by Cody6.2

The same engineers also said the larger lower grille on the 2014 let more air in. Yet if you actually look at it the actual opening is the same if not smaller than the 2010-2013.

I guarantee if you put a ZL1 rear tire on a 1LE that handling would be better not worse.

That is not the case with a 5th Gen. The 5th Gen understeers. Squaring the tires reduces understeer. The ideal tire for the 5th Gen is a 305/30/19. The same tires Pedders USA ran way back in 2009 and the same tire size you'll find on the yet to be released Z/28.

Originally Posted by Bozz1LE

The reason they are 285 is for neutral handling, cars with wider rear tires tend to be less consistent/predictable on the track. Running a square set of tires gives a better more in tune feel to the car and is much more predictable, 285 seems to be that nice medium.

Ive been running time trials, lapping days and autox's for about 10 years now and noticed that driving a car square set of tires gives you a bit more confidence as well.

The more grip you have in the front, the better.

Originally Posted by Arodr395

Does having the same tire size in the front and the rear make a car handle better and gives better times around the track? Or does having the tire stretched in the rear just create a better performing car around the track?

As long as the tire isn't over stretched it will be more predictable with reduced sidewall flex. In the front, the engineers opted for a bit more sidewall flex, to let the tire roll a bit more to increase grip when turning. The opposite is true in the rear. With the stretched sidewall you get a bit more rotation in the turns.

The L/28 uses a square wheel and tire setup.

[Cody6.2]

Originally Posted by JusticePete

That is not the case with a 5th Gen. The 5th Gen understeers. Squaring the tires reduces understeer. The ideal tire for the 5th Gen is a 305/30/19. The same tires Pedders USA ran way back in 2009 and the same tire size you'll find on the yet to be released Z/28.



The more grip you have in the front, the better.



As long as the tire isn't over stretched it will be more predictable with reduced sidewall flex. In the front, the engineers opted for a bit more sidewall flex, to let the tire roll a bit more to increase grip when turning. The opposite is true in the rear. With the stretched sidewall you get a bit more rotation in the turns.

The L/28 uses a square wheel and tire setup.

This has been covered a few times already.