Larger or just Wider contact patch?
03-21-2009, 11:01 PM
#1
Melting Slicks
Thread Starter
Larger or just Wider contact patch?
I remember reading in one of the car rags way back that increasing the width of a tire doesn't necesarily give more traction because the total area of the contact patch stays the same. Put another way, if you have a narrower tire the contact patch may look like a square, changing to wider tires makes the contact patch look like a rectangle - but the total area is the same. So are you really getting anything other than a 
factor?
factor?
03-21-2009, 11:09 PM
#2
Le Mans Master
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wrong. if you are running the right psi for the weight of the vehicle for a given tire size, the contact patch will be bigger and will remain the right dimension. You must also run the right design rim width for the tire in order to achieve that contact patch. A lot of folks make that mistake on the rim width. All they do is mushroom the tires tread surface by not running the right width.
03-22-2009, 12:35 AM
#4
Le Mans Master
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Its all about "pounds per square inch."
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
03-22-2009, 08:06 AM
#5
Instructor
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Its all about "pounds per square inch."
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
03-22-2009, 08:15 AM
#6
Team Owner
A wider tire, given the same conditions, will have a different shaped contact patch with the SAME area as the one you are comparing it to...
03-22-2009, 08:42 AM
#9
Racer
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Not to further complicate the issue but we are speaking of contact patch dimensions under a static loading condition. Depending upon speed relative to down force, g load, shoulder and side wall compliance/pliability, heat and the dynamic distribution of those many factors, the contact patch areas are decreased, increased and deformed as the vehicle is in motion. Given the above it may be wise to examine the aesthetic verses the practical benefits relative to driving style and needs. Tire technology is so
03-22-2009, 08:47 AM
#10
Team Owner
Not to further complicate the issue but we are speaking of contact patch dimensions under a static loading condition. Depending upon speed relative to down force, g load, shoulder and side wall compliance/pliability, heat and the dynamic distribution of those many factors, the contact patch areas are decreased, increased and deformed as the vehicle is in motion. Given the above it may be wise to examine the aesthetic verses the practical benefits relative to driving style and needs. Tire technology is so
03-22-2009, 09:10 AM
#11
Racer
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What about a simple picture? A 200 pound man with size 6 shoe prints will have a smaller contact patch than a 200 pound man with size 10 shoes. His weight is irrelevent; the amount of weight divided across his contact patch is dependent on the surface area of the patch--bigger patch, less psi within the patch, but total psi remains the same. Yes? I were walking across quicksand, I want to have big feet.
03-22-2009, 09:35 AM
#12
Its all about "pounds per square inch."
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
Setting physics aside (but not sure it's this simple), why does the lighter ZR1 get wider tires and pull more Gs? Additionally look how wide competition cars run tires...
03-22-2009, 09:44 AM
#13
Team Owner
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St. Jude Donor '15
"In honor of jpee"
I'm sure it exists somewhere, but I'd be interested in seeing the total contact "patch" of a typical, stock Corvette. And then, let's see what a properly "wheeled" and plus sized or or wider tires make as far as a contact patch.
Maybe this info exists on tirerack or Fed. DOT somewhere. I had read that the typical car (not necesarily the C6) has something like the equivalent of one, 8 1/2"x11" piece of paper for all 4 tires. Of course, that could be for a Cobalt.
Maybe this info exists on tirerack or Fed. DOT somewhere. I had read that the typical car (not necesarily the C6) has something like the equivalent of one, 8 1/2"x11" piece of paper for all 4 tires. Of course, that could be for a Cobalt.
03-22-2009, 09:54 AM
#14
Race Director
I remember reading in one of the car rags way back that increasing the width of a tire doesn't necesarily give more traction because the total area of the contact patch stays the same. Put another way, if you have a narrower tire the contact patch may look like a square, changing to wider tires makes the contact patch look like a rectangle - but the total area is the same. So are you really getting anything other than a factor?
factor?
03-22-2009, 09:58 AM
#15
Le Mans Master
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Im a tire engineer/testing engineer by trade, 30+ years, Fed. Govt. I have seen the variances in contact patches in testing, depending on the tires aspect ratio vs width. We conduct that on a "drive over glass plate". We vary the psi. Varience in as little as 3 psi can change the size of the contact patch.
Always remember, the tire is nothing but a pressure vessel. The air is what carries the load.
Todays radial tires are quite flexable, and lighter than previous radials due to the incorporation of denser, lighter components. When you go up in size, you increase the "pressure vessals interior volume" therefore the correct psi for the weight over the tire become critical in order to achieve the largest contact patch but also maintain the proper flexing action that the tires construction was built to accomplish. Sure, a low psi will give you a larger contact patch...but too low of a psi will create too much flex and can lead to premature tire failure.
Always remember, the tire is nothing but a pressure vessel. The air is what carries the load.
Todays radial tires are quite flexable, and lighter than previous radials due to the incorporation of denser, lighter components. When you go up in size, you increase the "pressure vessals interior volume" therefore the correct psi for the weight over the tire become critical in order to achieve the largest contact patch but also maintain the proper flexing action that the tires construction was built to accomplish. Sure, a low psi will give you a larger contact patch...but too low of a psi will create too much flex and can lead to premature tire failure.
03-22-2009, 10:08 AM
#17
Team Owner
Many wanna be engineers become business majors when the concept of the circle is factored into the lesson plan.....
03-22-2009, 10:16 AM
#18
CF Senior Member
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I wasn't a physics major but I'd rather have wider (than narrower) tires running a road course. The shape of the contact patch relates to the profile or aspect ratio of the wheel/tire. Our low profile tires have short wide contact patch for superior cornering and traction (not just for ). More conventional higher profile tires have a longer, narrower contact patch which would be better for a car plowing through snow.
Like I've heard, if you were to fall off a ten story building your best chance for survivability would be to land flatout...splayed on the ground to distibute the weight with less lbs per sq in.
). More conventional higher profile tires have a longer, narrower contact patch which would be better for a car plowing through snow.What about a simple picture? A 200 pound man with size 6 shoe prints will have a smaller contact patch than a 200 pound man with size 10 shoes. His weight is irrelevent; the amount of weight divided across his contact patch is dependent on the surface area of the patch--bigger patch, less psi within the patch, but total psi remains the same. Yes? I were walking across quicksand, I want to have big feet.
03-22-2009, 10:22 AM
#19
Le Mans Master
http://www.performancesimulations.co...on-tires-1.htm
It seems patch size is NOT directly related to anything.
It seems patch size is NOT directly related to anything.
03-22-2009, 10:22 AM
#20
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Its all about "pounds per square inch."
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
If two tires, one wider than the other, are at the same inflation pressure, they will support the same amount of vehicle weight, with the same amount of contact to the ground.
If the car weighs 4000lbs, and each corner is the same weight, then each tire supports 1000 lbs. If the inflation pressure is 33.3 psi, then each tire would need a support base (contact patch) of 30 square inches to equal the 1000lb weight.
The "thirty" inches of contact patch can be 6 inches wide and 5 inches long (skinny tire), or 10 inches wide and three inches long (wider tire).
Either way, there is 1000 pounds excerted on the tire, and in response the tire is pushing back a 33.3 pounds per square inch, requiring 30 square inches of support base to do the job.
Class is OVER
Rubber is funny stuff, and modern tire technology is very complex. The only way to know for sure how two tires compare is to test them.