Tire ratios question
Thread Starter
Instructor
Joined: Jan 2020
Posts: 148
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From: Texas
Tire ratios question
Ordered a set up Michelin PS4S tires for my widebody c7 the sizes are 295-30-19 Front and 325-25-20 Rear.
Ratio comes out to 1.016 for the set.
This ratio shouldn't cause any issues right?
Ratio comes out to 1.016 for the set.
This ratio shouldn't cause any issues right?
Melting Slicks
Joined: Oct 2009
Posts: 2,560
Likes: 485
From: Moberly, Mo
If your just an inch over all between the fronts and the rear your fine. Over 2 inches you run into problems with abs and traction control when you exceed that number.
Last edited by 99vetteran; May 28, 2021 at 08:19 AM.
Le Mans Master
Joined: Aug 2007
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From: Orange Park FL
Tech Contributor
Joined: Oct 1999
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From: Charlotte, NC (formerly Endicott, NY)
Stock ratio is 1.037 you may still be fine since you are within 4% of the stock ratio. What you could happen and it would be hard to detect is an early onset of TC intervention. To the EBCM the rear wheels are going to look like they're spinning slightly due to a higher than normal rear-wheel speed compared to the front wheel speeds. In a situation where grip is a little low, the tires might slip just a little and you would be into a full TC intervention Vs none or maybe a little relaxation of engine torque.
I think ABS might have an initial over or under reaction depending on whether the wheel that indicates it is locking up is on the front or rear. Stability control activation is based on steering wheel angle and how fast or slow the car yaws to follow the direction from the steering wheel. Where wheel diameter affects it is when the EBCM determines how hard to apply one of the brakes to correct yaw.
For run of the mill street driving without any emergency at the limit of adhesion maneuvers, you will never notice an issue.
Bill
I think ABS might have an initial over or under reaction depending on whether the wheel that indicates it is locking up is on the front or rear. Stability control activation is based on steering wheel angle and how fast or slow the car yaws to follow the direction from the steering wheel. Where wheel diameter affects it is when the EBCM determines how hard to apply one of the brakes to correct yaw.
For run of the mill street driving without any emergency at the limit of adhesion maneuvers, you will never notice an issue.
Bill
Last edited by Bill Dearborn; May 28, 2021 at 09:59 PM.
Thread Starter
Instructor
Joined: Jan 2020
Posts: 148
Likes: 21
From: Texas
Stock ratio is 1.037 you may still be fine since you are within 4% of the stock ratio. What you could happen and it would be hard to detect is an early onset of TC intervention. To the EBCM the rear wheels are going to look like they're spinning slightly due to a higher than normal rear-wheel speed compared to the front wheel speeds. In a situation where grip is a little low, the tires might slip just a little and you would be into a full TC intervention Vs none or maybe a little relaxation of engine torque.
I think ABS might have an initial over or under reaction depending on whether the wheel that indicates it is locking up is on the front or rear. Stability control activation is based on steering wheel angle and how fast or slow the car yaws to follow the direction from the steering wheel. Where wheel diameter affects it is when the EBCM determines how hard to apply one of the brakes to correct yaw.
For run of the mill street driving without any emergency at the limit of adhesion maneuvers, you will never notice an issue.
Bill
I think ABS might have an initial over or under reaction depending on whether the wheel that indicates it is locking up is on the front or rear. Stability control activation is based on steering wheel angle and how fast or slow the car yaws to follow the direction from the steering wheel. Where wheel diameter affects it is when the EBCM determines how hard to apply one of the brakes to correct yaw.
For run of the mill street driving without any emergency at the limit of adhesion maneuvers, you will never notice an issue.
Bill
