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GS/Z06 tire sizes on a base model Corvette? Noticeable improvement in handling?

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GS/Z06 tire sizes on a base model Corvette? Noticeable improvement in handling?

 
Old 02-14-2019, 01:37 PM
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car2fast4you
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Default GS/Z06 tire sizes on a base model Corvette? Noticeable improvement in handling?

I have a base model Corvette - but my custom wheels are 1" wider than stock. I'm running stock tire sizes now. I am considering going with GS/Z06 tire sizes - 275-35-18 in front, and 325-30-19 in the rear.

For those of you who have switched to GS/Z06 tires on your base model, I have a few questions....

1. Did you notice a significant difference in how the car handles?
2. Does the steering feel different?
3. Did it effect your gas mileage?
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Old 02-14-2019, 03:43 PM
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captain vette
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the GS and Z06 body is over 3 inches wider than a base c6 body, i think it would not look good.
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Old 02-14-2019, 04:18 PM
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Originally Posted by captain vette View Post
the GS and Z06 body is over 3 inches wider than a base c6 body, i think it would not look good.
My wheels have the proper offset to accommodate the extra tire width. So, I'm not concerned about the look. And, by the way, the tires are about 2 inches wider.

I just want to know if the handling benefits are significant enough compensate for the extra unsprung weight & cost.
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Old 02-15-2019, 11:37 AM
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Originally Posted by car2fast4you View Post
My wheels have the proper offset to accommodate the extra tire width. So, I'm not concerned about the look. And, by the way, the tires are about 2 inches wider.

I just want to know if the handling benefits are significant enough compensate for the extra unsprung weight & cost.
I went from a 2008 Z51 optioned base vette to a 2011 GS vette in 2011, and on the street, it was some difference in handling, but you need to also change brakes, sway bars, etc. to get the full benefit.

It also depends on tire brand/type too. Meaning you can buy base vette size tires that will outperform certain GS/Z06 sizes.

Offset to get the rims/tires on the car only mean that you will chew off your fender lips the first time you go around a curve fast, because they will HAVE to stick out some if you want to miss the inner fender liners.

That's why the GS/Z06 has bigger fenders over the base C6.

Now, for your other questions - partial answer because I was going from a base to GS, the steering felt the same, and gas mileage went down a couple mpg

Last edited by Seadawg; 02-15-2019 at 11:40 AM.
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Old 02-15-2019, 12:35 PM
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Depends on the type of tires. I run rear dot nitto drag radials and there is night and day difference. If you’re just talking about street tires you’d have to be hanging it out on the egde all the time to notice a difference .
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Old 02-15-2019, 04:31 PM
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I run 275/35-18 Michelin pilot super sports on 18 x 9.5" front and 295/35-19 MPSS ON 19 x 11" rear. I have A LOT more grip than stock. There is also more oversteer, due to less of a front to rear stagger - which I like.

I wanted the largest front tire that is also ideal for a 9.5" wide wheel. I did not want to go with 325 rear, so as to reduce the stagger. 305 and 315 weren't good options.

Given the near perfect weight balance of a c6, GM likely used 245 width fronts and a large front to rear stagger as a safety measure, to induce understeer. Putting too little tire on the front seems to be a common approach by manufacturers, for safety considerations. Understeer is considered safer than oversteer

With 325 rears, you'll likely see the increase in grip I see, though you will retain more understeer at the limit, given the large front to rear stagger. The limit will be higher though than with stock sizes, assuming you buy good quality summer only tires.

Check tread width dimensions, as some tires are wider than others in the same size and they may also have a more squared off shoulder. Both factors may affect how well it fits your car.
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Old 02-15-2019, 04:37 PM
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Forgot to add, hopefully your new wheels and tires are lighter than stock. Adding significant weight could adversely affect performance.
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Old 02-15-2019, 05:15 PM
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are you also planning on reprogramming the PCM?
if you going up in tire size ( diameter ), this would effect your mileage, I would expect a small increase.
although the added weight ( from a larger tire ) might offset that somewhat.
the larger diameter would effect your speedometer reading.
can you get enough offset to keep the tire within the fender lip? if so, what about inner clearance (frame & fender well )?
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Old 02-15-2019, 05:27 PM
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The up-sizes being considered represent almost no change in diameter, therefore no reprogramming needed.
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Old 02-15-2019, 05:44 PM
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if the aspect ratios are such, then I agree. but I would still be concerned with the offset rims.
he may be gaining fender clearance, but at the expense of frame & suspension interference.
as noted above, their is a reason why the Z06, G/S and, ZR1's are fender flares ( maybe no room on the inner side of fenders ).
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Old 02-15-2019, 07:10 PM
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It depends on your use. Of you track the car a lot, then there is an argument to be made that it's worth it. If the car is just a cruiser, then no. The speeds necessary to see the benefit in handling are just not safe, legal, or plausible on the street.

What you will likely see is a reduction in turn in speeds, so it will actually feel like the car handles worse

Tldr; If you're not tracking the car, you're not bumping into the stock handling limits, and the extra tire will yield no gains.
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Old 02-15-2019, 10:18 PM
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I went from the base tires to 265's in front and 305's in the rears.
I also went from run flats to non run flats and lighter rims.

Benefits:
1. Weight reduction 2-3 lbs. per corner.
2. Improved traction, handling and braking with wider contact patch.
3. Speedo needed to be reprogramed because the speedo read 2.5 mph faster at 60 mph.
4. I did not change the sway bars because the Z51 suspension has the same size front sway bar as the GS/Z06. The rear is only slightly smaller and I am not running 325's as the GS/Z06.
5. Steering felt about the same, keep in mind I reduced weight at each corner.
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Old 02-15-2019, 11:14 PM
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Thanks for all the comments guys......plenty to consider.
My current wheels are iForged monoblock - but I'm not sure how much weight savings there was vs. OEM - because I started with Gumby's, which I believe were also forged.
I'm also running Continental ExtremeContact DW summer tires (non-run-flat), in stock sizes. They were one of the lightest tires you could get, at the time. And they were certainly lighter than the OEM run-craps.

I've been doing A LOT of research on tires. I've been trying to decide on whether to get a 2nd set of wheels to run (with all-season tires) during the colder months. Or, I may decide to try some all-season tires to see if I can live with them year-round....since I never track the car. It just happens that the Michelin Pilot Sport A/S 3+ tires come in Z06/GS sizes (but in run-flats only). So....I got to thinking that the extra tire width may compensate for some of the loss of traction due to them being all-season. Anyway.....here is some interesting tire information that I put into a spreadsheet to help me make a decision.....or maybe just further confuse me.....



What you'll notice is that the Michelin Pilot Sport 4S summer tires in a Z06/GS sizes weigh about the same as the all-season tires in OEM base sizes....give or take a pound or two. If you compare summer versus summer tires - the wider tires will generally add about 2-3 pounds per tire, which shouldn't be noticeable on the road.

HOWEVER - The all-season Michelin in the Z06/GS sizes (come in RUN-FLAT only) weighs about 10 POUNDS (yikes!) more than the all-season tires in OEM base sizes. That also means that those tires would weigh 12-13 pounds (each) more than the summer tires that I have now. I may never notice the difference in the weight, but I could never justify adding 40-50 pound in total unsprung weight to my car for no good reason.

Anyway....based on everyone's comments, I'm leaning towards sticking with the stock tire sizes.

Last edited by car2fast4you; 02-15-2019 at 11:19 PM.
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Old 02-15-2019, 11:48 PM
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Originally Posted by EVRGRN View Post
I run 275/35-18 Michelin pilot super sports on 18 x 9.5" front and 295/35-19 MPSS ON 19 x 11" rear. I have A LOT more grip than stock. There is also more oversteer, due to less of a front to rear stagger - which I like.

I wanted the largest front tire that is also ideal for a 9.5" wide wheel. I did not want to go with 325 rear, so as to reduce the stagger. 305 and 315 weren't good options.

Given the near perfect weight balance of a c6, GM likely used 245 width fronts and a large front to rear stagger as a safety measure, to induce understeer. Putting too little tire on the front seems to be a common approach by manufacturers, for safety considerations. Understeer is considered safer than oversteer

With 325 rears, you'll likely see the increase in grip I see, though you will retain more understeer at the limit, given the large front to rear stagger. The limit will be higher though than with stock sizes, assuming you buy good quality summer only tires.

Check tread width dimensions, as some tires are wider than others in the same size and they may also have a more squared off shoulder. Both factors may affect how well it fits your car.

Thanks Evrgrn,
That all makes a lot of sense to me. And I agree completely regarding the different tread widths & shoulder shapes of the various tires. Going with a tire with more rounded shoulders may make the 325's a better fit....if I go that route.

In a summer tire I would likely just bump up the widths slightly to 255 and 295 to fit a little better on my 9 1/2" and 11" rims. The stock width tires are slightly stretched, which isn't my favorite look.

Last edited by car2fast4you; 02-15-2019 at 11:49 PM.
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Old 02-16-2019, 02:29 AM
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The McLaren P1, LaFerrari, most Paganis, 918, Valkyrie, Agera R (345) etc... all run smaller tires. The 1500hp Bugatti Chiron runs 355. You don’t need the wide tires.

This obsession with a wall of rubber is strange. Learn to launch.
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Old 02-16-2019, 12:02 PM
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Originally Posted by ProfessorDeath View Post
The McLaren P1, LaFerrari, most Paganis, 918, Valkyrie, Agera R (345) etc... all run smaller tires. The 1500hp Bugatti Chiron runs 355. You don’t need the wide tires.

This obsession with a wall of rubber is strange. Learn to launch.

No, just all wheel drive! Many of these super cars are running hybrid set ups with electric power controlling the front axle.

Last edited by Mike's LS3; 02-16-2019 at 12:08 PM.
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Old 02-17-2019, 10:31 AM
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Originally Posted by car2fast4you View Post
In a summer tire I would likely just bump up the widths slightly to 255 and 295 to fit a little better on my 9 1/2" and 11" rims. The stock width tires are slightly stretched, which isn't my favorite look.
255/295 is also a popular option, with many people doing those sizes on stock width wheels. Bear in mind that those tires will also have a stretched look on 9.5" and 11" wide wheels. The 295/35-19 on my 11" wheel is a little stretched still. The 275/35-18 looks great on the 9.5" wheel though. In addition to the performance benefit, I love the look of a wide front tire/wheel combo.

Another option that is well supported by your wheel widths is 265/35-18 front and 305/30-19 rear. There will be a small speedo error (due to smaller diameter rear tire), though the front to rear diameter difference is still within range to keep active handling and traction control happy.

Last edited by EVRGRN; 02-17-2019 at 10:31 AM.
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