Correct Tire Ratio Front to back
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
Correct Tire Ratio Front to back
I have a C6 coupe running 15s out back on a 325/50/15 (28" tall)
my fronts are weld 18x7s. I am trying to figure out what the correct front to back tire ratio is so that i can order front tires... can anyone point me in the right direction?
my fronts are weld 18x7s. I am trying to figure out what the correct front to back tire ratio is so that i can order front tires... can anyone point me in the right direction?
Le Mans Master
Joined: Apr 2011
Posts: 7,821
Likes: 412
From: Montreal
St. Jude Donor '13
Measure the actual tire on the car, don't go by what the specs say.
I run 325/45/17 in back. The specs say 28 inch but they measure at 27 on the car.
In front I have 18 x 7 Welds with 225/45/18s
All works well with no issues.
I run 325/45/17 in back. The specs say 28 inch but they measure at 27 on the car.
In front I have 18 x 7 Welds with 225/45/18s
All works well with no issues.
Melting Slicks
Joined: Jan 2013
Posts: 2,837
Likes: 41
From: Dallas Tejas
I'm running 245/45/18 Invos up front and 305/35/19 ET streets out back. I got the engine drag warning once, hasn't come back since. No active handling issues or traction control issues have presented themselves.The 305/35/19 ET street is a 27.4" tire IIRC I forget the measurement of the stock stagger but the computer allows some variance. One guy said he had as much as 3%, but who knows if that is legit or not.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
How well does the car stop with the narrow 225s up front? assuming you have stopped it from faster than your 1/4 mile speeds?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
I'm running 245/45/18 Invos up front and 305/35/19 ET streets out back. I got the engine drag warning once, hasn't come back since. No active handling issues or traction control issues have presented themselves.The 305/35/19 ET street is a 27.4" tire IIRC I forget the measurement of the stock stagger but the computer allows some variance. One guy said he had as much as 3%, but who knows if that is legit or not.
Le Mans Master
Joined: Apr 2011
Posts: 7,821
Likes: 412
From: Montreal
St. Jude Donor '13
Up here if you get caught at that speed, they take your car, your license, and your first born. I just cant afford the chance.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,368
Likes: 30
From: dfw Texas
im in the same boat as your.. Wide rear.. narrow front with z51s.
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Melting Slicks
Joined: Jan 2013
Posts: 2,837
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From: Dallas Tejas
It's just a notice letting you know that engine braking will be reduced. It'll pop up on the hud saying to check gauges.. The DIC will just say engine drag or whatever the warning is.
Melting Slicks
Joined: Jan 2013
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From: Dallas Tejas
Le Mans Master
Joined: Dec 2005
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From: Southeast TX
If you want to hit it dead nuts, look at the revolutions per mile. The stockers have a 1.046 front to rear ratio. The fronts are turning 1.046 times as fast as the rears. Fronts turn 813 revs/mile while the rears are turning 777/mile. Most tires have the revs/mile info available. The tire height can fool you depending on the air pressure in the tire. At a lower air pressure, the tires are shorter, but the circumference and revs/mile go down very little.
Then you get into some tires "growing" as tire rpm goes up. Not an exact deal, but you can come close and keep the pcm happy.
Then you get into some tires "growing" as tire rpm goes up. Not an exact deal, but you can come close and keep the pcm happy.
Team Owner
Joined: Mar 2008
Posts: 21,502
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From: Southern Utah
If you want to hit it dead nuts, look at the revolutions per mile. The stockers have a 1.046 front to rear ratio. The fronts are turning 1.046 times as fast as the rears. Fronts turn 813 revs/mile while the rears are turning 777/mile. Most tires have the revs/mile info available. The tire height can fool you depending on the air pressure in the tire. At a lower air pressure, the tires are shorter, but the circumference and revs/mile go down very little.
Then you get into some tires "growing" as tire rpm goes up. Not an exact deal, but you can come close and keep the pcm happy.
Then you get into some tires "growing" as tire rpm goes up. Not an exact deal, but you can come close and keep the pcm happy.
Revs per mile is a stat that is available for most tires and is right there on the Michelin website. It is a very good way to keep the computer happy.