Question: Tire aspect effect

FlukeSS · 03-31-2021, 06:30 PM

Is there any major issue if your front tires have a 40 aspect ratio vs the rear tires having a 30 aspect ratio?

Reason: Looking to replace my rear wheels with 20x11 ET 43's with 305/30R20's

Thanks,

FlukeSS

Getnlwr · 03-31-2021, 06:40 PM

As long as you don't stray far from the overall diameter you shouldn't have an issue.

FlukeSS · 03-31-2021, 06:41 PM

Quote:

Originally Posted by Getnlwr

As long as you don't stray far from the overall diameter you shouldn't have an issue.

Ty, I plan to do the 20x10 fronts as well just not right now.

I just wanted to make sure I didn't have anything major to worry about.

Getnlwr · 03-31-2021, 08:09 PM

The computers algorithm for ABS and TC is likely something that will get messed up if the percentages are way out of whack. The only number the computer cares about is based on the overall diameter, or revolutions per mile (same thing). Hope it all works out.

Homer2 · 03-31-2021, 08:21 PM

just toss the sizes into a tire size calculator - and Bob's your uncle

arpad_m · 03-31-2021, 08:31 PM

Speedo will be 1.4% off and the look of the tires a bit strange (front sidewall remains 3.9" vs rear going from 3.8" to only 3.6"), but other than that, you'll be fine, nothing else should happen.

chaospiece · 04-01-2021, 04:04 PM

You have to be within 2% difference in diameter of front and rear wheels or you will throw a stabilitrack code and go into limp mode.
If you're lucky enough not to always trigger limp mode, youll start to feel stabilitrack braking randomly trying to keep same rotation ratio. It's pretty annoying.

Went through it several times just trying out different sizes and manufacturers for fun.

ctrlz · 04-02-2021, 10:29 AM

Quote:

Originally Posted by chaospiece

You have to be within 2% difference in diameter of front and rear wheels or you will throw a stabilitrack code

Yes. This seems to be going around.
recent thread in the tire sub-forum:
https://www.camaro6.com/forums/showthread.php?t=589253

keep in mind, the car has no idea what size tires are on the wheels. You can slightly tweak the effective tire diameter using tire pressure. So if your tire choice is on the edge of throwing a code, you might be able to run +2 psi up front and -2 psi in back or vice-versa.

Spaceme1117 · 04-02-2021, 10:36 AM

Quote:

Originally Posted by FlukeSS

Is there any major issue if your front tires have a 40 aspect ratio vs the rear tires having a 30 aspect ratio?

Reason: Looking to replace my rear wheels with 20x11 ET 43's with 305/30R20's

Thanks,

FlukeSS

I depends. The apect ratio is the tire sidewall height as a percentage of the tire width.

So two tires with 30 aspect ratio can have completely different sidewall heights if the tires widths are very different.

Main thing is to try to keep the tire diameter as close to stock as possible.

Norm Peterson · 04-02-2021, 12:21 PM

Quote:

Originally Posted by FlukeSS

Is there any major issue if your front tires have a 40 aspect ratio vs the rear tires having a 30 aspect ratio?

Reason: Looking to replace my rear wheels with 20x11 ET 43's with 305/30R20's

Thanks,

FlukeSS

Your car should have come with 245/40-20 front tires and 275/35-20 rear tires.

I'm pretty sure that your rear wheels are no wider than 9.5", which is a whole inch narrower than any 305/30-20 tire should ever be squeezed onto. If you want 305-wide tires, get wheels that are 10.5" or 11" wide.

Norm

Fraxum · 04-02-2021, 12:49 PM

OP if you want your speedo to be correct without tuning then make sure the tire is right around 27.5" high. And this is really important in the front where if you go taller you will most likely need spacers. Been there done that.

If you do go with a taller tire the difference between the front and back cannot be more than an inch, otherwise stabilitrac will get very upset.

delthawk5 · 04-02-2021, 01:58 PM

Personally wouldn't **** with it.

LT4Greg · 04-03-2021, 10:54 AM

I don’t understand why people don’t use the TireSize.com website to check and see what sizes of tires are compatible with the stock sizes. It lets you compare different sizes and tells how much the speedometer will be off. They cover different size wheels too. I used the website when I had my 2016 2SS and was looking at going to a different size rear tire on the stock wheels. I had 285/35s installed and didn’t have any issues. Good luck to the Op.

Norm Peterson · 04-03-2021, 02:10 PM

Quote:

Originally Posted by LT4Greg

I don’t understand why people don’t use the TireSize.com website to check and see what sizes of tires are compatible with the stock sizes.

Not everybody brings a numbers-oriented mindset to the matter of choosing tires. Isolated scraps of understanding at best, nothing about how they all fit together.

No flame intended, that's just the way it's been pretty much forever.

Norm

03-31-2021, 06:30 PM	#1
FlukeSS Drives: 2020 Camaro 2SS A10 Join Date: Jun 2018 Location: Here Posts: 1,809	Question: Tire aspect effect Is there any major issue if your front tires have a 40 aspect ratio vs the rear tires having a 30 aspect ratio? Reason: Looking to replace my rear wheels with 20x11 ET 43's with 305/30R20's Thanks, FlukeSS

03-31-2021, 06:40 PM	#2
Getnlwr Drives: '21 ZL1 A10 '08 SRT10 Join Date: Apr 2019 Location: Washington Posts: 132	As long as you don't stray far from the overall diameter you shouldn't have an issue. __________________ 2021 ZL1 A10 in Satin Steel Metallic, 2008 Viper Vert M6 in Venom Red, 2018 ZL1 A10 in Bumblebee Yellow (SOLD)

03-31-2021, 08:09 PM	#4
Getnlwr Drives: '21 ZL1 A10 '08 SRT10 Join Date: Apr 2019 Location: Washington Posts: 132	The computers algorithm for ABS and TC is likely something that will get messed up if the percentages are way out of whack. The only number the computer cares about is based on the overall diameter, or revolutions per mile (same thing). Hope it all works out. __________________ 2021 ZL1 A10 in Satin Steel Metallic, 2008 Viper Vert M6 in Venom Red, 2018 ZL1 A10 in Bumblebee Yellow (SOLD)

03-31-2021, 08:21 PM	#5
Homer2 Drives: 50th Anni.. coming home 11/01 Join Date: Jul 2014 Location: Toronto. Ontario Posts: 1,640	just toss the sizes into a tire size calculator - and Bob's your uncle __________________ ##################### Built Sept 16/2016 - #2681 of 5955. She came home with me 11/01/16. 50th Anni, 2SS, A8, NPP, NGM Rock Guards, Footwell Lighting, Black Bow Ties, Street Warrior Rotors and Pads, Ceramic Pro, 3M PPF, Oracle Ghosted Side Markers, Kooks 2" headers w/hi flow cats. GPI Stage 1 Cam installed at 305,000 kms.

03-31-2021, 08:31 PM	#6
arpad_m Drives: 2018 Camaro 2SS A8 Join Date: Jul 2017 Location: East Tennessee Posts: 13,151 View My Garage	Speedo will be 1.4% off and the look of the tires a bit strange (front sidewall remains 3.9" vs rear going from 3.8" to only 3.6"), but other than that, you'll be fine, nothing else should happen. __________________ 2018 Camaro 2SS — G7E MX0 NPP F55 IO6 735 rwhp \| 665 rwtq Magnuson TVS 2300 80mm pulley \| Kooks 1 7/8" LT headers \| JRE smooth idle terminator cam \| LT4 FS & injectors \| TSP forged pistons & rods JMS PowerMAX \| DSX flex fuel kit \| Roto-Fab CAI \| Soler 95mm LT5 TB \| 1LE wheels \| 1LE brakes \| BMR rear cradle lockout \| JRE custom tune 1100 - 1/30/18 \| 2000 - 1/31/18 3000 - 2/06/18 TPW 2/26/18 3400 - 2/19/18 \| 3800 - 2/26/18 4300 - 2/27/18 \| 4B00 - 3/01/18 4200 - 3/05/18 \| 4800 - 3/14/18 5000 - 3/16/18 \| 6000 - 3/19/18

04-01-2021, 04:04 PM	#7
chaospiece Drives: 2018 SS, 2016 GT Join Date: Mar 2018 Location: California Posts: 210	You have to be within 2% difference in diameter of front and rear wheels or you will throw a stabilitrack code and go into limp mode. If you're lucky enough not to always trigger limp mode, youll start to feel stabilitrack braking randomly trying to keep same rotation ratio. It's pretty annoying. Went through it several times just trying out different sizes and manufacturers for fun.

04-02-2021, 12:49 PM	#11
Fraxum Drives: a M6 LT1 ordered From Becky!!! Join Date: Jan 2010 Location: NJ Posts: 7,520	OP if you want your speedo to be correct without tuning then make sure the tire is right around 27.5" high. And this is really important in the front where if you go taller you will most likely need spacers. Been there done that. If you do go with a taller tire the difference between the front and back cannot be more than an inch, otherwise stabilitrac will get very upset. __________________ "Democracy Dies in Darkness" My LT1 Keeper ..... ..... My Car Blog CarPlayList, a free App to build USB and Android Music drives.

04-02-2021, 01:58 PM	#12
delthawk5 Drives: 2019 2SS Crush Join Date: Jun 2020 Location: Denver, CO Posts: 163	Personally wouldn't **** with it. __________________ 2019 2SS Crush Orange - NPP - 2016 BMW 4 Series Gran Coupe \| 2013 Genesis 3.8 R-Spec \| 2012 Scion FR-S

04-03-2021, 10:54 AM	#13
LT4Greg Drives: 2017 Camaro ZL1 Coupe Join Date: May 2016 Location: Georgia Posts: 5,869	I don’t understand why people don’t use the TireSize.com website to check and see what sizes of tires are compatible with the stock sizes. It lets you compare different sizes and tells how much the speedometer will be off. They cover different size wheels too. I used the website when I had my 2016 2SS and was looking at going to a different size rear tire on the stock wheels. I had 285/35s installed and didn’t have any issues. Good luck to the Op. __________________ ZL1 Coupe, PDR, Exposed carbon fiber hood insert, My Link with Nav, M6 6 speed and Silver Ice Metallic. Mods done: ceramic window tint, GM Accessories Camaro floor mats and Roto-Fab CAI.

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