Why did the 6th gen SS 1LE get wider tires at the rear only?

[Norm Peterson]

Given that the 5th gen 1LE and Z/28 both ran same-size tires at all four corners, I'm wondering what changed the philosophy specifically for the 6th gen SS 1LE away from maintaining the same tire size all around and simply making the rear wheels a little wider than the fronts.

Was it a downstream consequence of the bump in power and torque? Understeer budget or breakaway characteristics reasons and the Alpha chassis? Appearance? Other?


Norm

[RacerX78]

Fitting 20" 305s all the way around is not possible without modifying fenders up front. Even the ZL1 1LE has wider front fenders, 19" wheels & narrower front suspension to fit 305s upfront.

[Norm Peterson]

The question is really about why they widened the rear tires at all, if they were going to leave the fronts alone.


Norm

[DGthe3]

Originally Posted by Norm Peterson

The question is really about why they widened the rear tires at all, if they were going to leave the fronts alone.


Norm

Presumably because it still offers more overall grip than not putting wider tires out back.

[RacerX78]

Originally Posted by Norm Peterson

The question is really about why they widened the rear tires at all, if they were going to leave the fronts alone.


Norm

The fronts haven't been left alone. The standard SS gets 20x8.5" 245mm tires up front. The 1LE has 20x10" 285mm up front. So front grip has been upgraded and tuned to match the rear end grip.

[Kise]

Originally Posted by Norm Peterson

The question is really about why they widened the rear tires at all, if they were going to leave the fronts alone.


Norm

to the 1le- my 2ss has larger wheels in the rear as well.

if you notice on drag cars or slicks how the tires are really wide on the back.. same situation.

larger surface = better grip overall, especially on a launch.
more hp and torque means less grip for rwd cars.

[Norm Peterson]

Originally Posted by DGthe3

Presumably because it still offers more overall grip than not putting wider tires out back.

Adding all of however much total grip increase at the rear is heavier understeer, particularly up near the limit (all else held constant). I'm not aware of any complaints that handling for the 5th gen 1LE was "too loose", so I'm not seeing an existing condition that needed to be fixed.


Norm

[Norm Peterson]

Originally Posted by RacerX78

The fronts haven't been left alone. The standard SS gets 20x8.5" 245mm tires up front. The 1LE has 20x10" 285mm up front. So front grip has been upgraded and tuned to match the rear end grip.

I'm comparing 6th gen SS 1LE against the 5th gen 1LE, not against the standard SS. Handling top-dogs only.


Norm

[Norm Peterson]

Originally Posted by Kise

to the 1le- my 2ss has larger wheels in the rear as well.

if you notice on drag cars or slicks how the tires are really wide on the back.. same situation.

larger surface = better grip overall, especially on a launch.
more hp and torque means less grip for rwd cars.

I'm well aware of the 20" wheel and tire staggering that the non-1LE SS has had since, what, day 1 of the 5th gen?

What I'm looking at here is strictly the cornering & handling side. Straight line stuff at the SS level is a mission for the non-1LE SS with A10.

If Chevy is trying to squeeze a bit more straight line capability into these cars that are primarily not about the straight line, that would fall under the "other" catch-all.


Norm

[Ryephile]

Originally Posted by Norm Peterson

...Was it a downstream consequence of the bump in power and torque? Understeer budget or breakaway characteristics reasons and the Alpha chassis? Appearance? Other?


Norm

Sounds like a good "Ask Al" submission.

Given how snug the fitment is with the 285's in non-ZL1 fenders, to me that's likely the primary limitation.

[vtirocz]

This question was asked to Al during the last Camaro Fest in Bowling Green. He said that they tested several different options, including a square setup like the 5th gen SS 1LE, and they were able to get faster lap times and overall better handling characteristics with the setup they chose. The practical benefits of the square setup were offset by the better performance characteristics of the staggered setup.

Keep in mind that the 6th gen suspension geometry and chassis are different from the 5th gen, so what worked well on one may not work well on the other.

[RacerX78]

Originally Posted by Norm Peterson

I'm comparing 6th gen SS 1LE against the 5th gen 1LE, not against the standard SS. Handling top-dogs only.


Norm

Well given that the 5th and 6th Gen cars are on completely different chassis, engine, and suspension. It doesn't make since to compare the two. You might as well as why the mustang and camaro don't run the same wheel size setup. A closer comparison would be between the ATS-V and the Camaro given they are on the same platform.

Originally Posted by Norm Peterson

Adding all of however much total grip increase at the rear is heavier understeer, particularly up near the limit (all else held constant). I'm not aware of any complaints that handling for the 5th gen 1LE was "too loose", so I'm not seeing an existing condition that needed to be fixed.

Norm

Unlike the mustang that had multiple aspects carried over from various generations (SN95, S197, etc) The Alpha platform was entirely new as well was the LT1. So unlike before they started from a different standpoint handling wise. With the Alpha being small, lighter and stiffer than the previous chassis different strategies would be used to setup the handling for both the base and higher performance cars.

Plus you also want to run a tire as narrow as possible for your traction/handling requirements. As wider tires add friction, drag & weight. Reason like that is why you don't see F1/Indy cars running a square stance.

[Ryephile]

Originally Posted by RacerX78

...Reason like that is why you don't see F1/Indy cars running a square stance.

No, F1 cars don't run square because their rules disallow it. It's an entirely different topic.

[JeffFox]

Originally Posted by Norm Peterson

Given that the 5th gen 1LE and Z/28 both ran same-size tires at all four corners, I'm wondering what changed the philosophy specifically for the 6th gen SS 1LE away from maintaining the same tire size all around and simply making the rear wheels a little wider than the fronts.

Was it a downstream consequence of the bump in power and torque? Understeer budget or breakaway characteristics reasons and the Alpha chassis? Appearance? Other?


Norm

Depending on the depth of Al's answer this might provide some guidance to owners purchasing wheels and tires for different applications.