start with pressure at placard - drive thru sand/dirt on the road then see how the tire is painted. I creep up the pressure in 0,5 psig increments until the is no dirt/sand painting the tread wraparound of the side wall. This would be your min operating pressuure on a minimally laden vehicle using radial tyre with sidewall stiffeners. Ballon tires will have dynamically increased expanded tread width.
Center Tread Wear....
- Thread starter badtlc
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On my Jetta, I ran I think 4 sets of Conti ContactPro or whatever OEM tires at 40psi IIRC and got nice even albeit fast wear (40k if I ran to the wear bars). I was not driving very much for mpg, but generally I don't slow down for turns either. Lots of hard cornering to keep wear even? Not really, just typical highway stuff, but perhaps.
This recent set of enTyres though do not like 40psi, they are wearing faster in the middle. So I either need to start driving harder, or let some air out.
Hard to say if I wind up saving money or not... If the edges aren't far behind the center, then I've likely given up little life. As it is, wet traction is getting compromised before getting close to the legal wear bars; as such I've only run tires to wear bars when I'm being really cheap (and didn't mind driving slower in the rain to compensate).
This recent set of enTyres though do not like 40psi, they are wearing faster in the middle. So I either need to start driving harder, or let some air out.
Hard to say if I wind up saving money or not... If the edges aren't far behind the center, then I've likely given up little life. As it is, wet traction is getting compromised before getting close to the legal wear bars; as such I've only run tires to wear bars when I'm being really cheap (and didn't mind driving slower in the rain to compensate).
It sounds like type of tire on the same car can make a difference. Does anyone have any idea what the differences in tire construction would be that would allow this different tread wear at same PSIs?
Arco,
What you suggest sounds great. I think that would be the best method. Unfortunately, I don't think I have a way of doing that.
Arco,
What you suggest sounds great. I think that would be the best method. Unfortunately, I don't think I have a way of doing that.
Originally Posted By: badtlc
Originally Posted By: eljefino
Maybe your alignment or driving style doesn't sacrifice the corner/shoulders of the tire when turning. In other words the "over" inflation is to compensate for just wearing the corners right off.
Alignment gets checked regularly, so that should be good.
Driving style could be part of it. My cars see easy miles. It isn't all highway, but neither me or my wife take corners as fast as possible.
I suppose I misspoke. I guess I meant "suspension setup" and in particular how the steering tires "hunker down" when cornering. A double wishbone is usually pretty good at giving lots of negative camber on the outside wheel so when it folds over on itself, its closer to parallel with the road surface.
Also different tires of the same theoretical size have different profiles on the corner and stiffness in the belts which may or may not hold in that "center bulge" you're suffering.
Originally Posted By: eljefino
Maybe your alignment or driving style doesn't sacrifice the corner/shoulders of the tire when turning. In other words the "over" inflation is to compensate for just wearing the corners right off.
Alignment gets checked regularly, so that should be good.
Driving style could be part of it. My cars see easy miles. It isn't all highway, but neither me or my wife take corners as fast as possible.
I suppose I misspoke. I guess I meant "suspension setup" and in particular how the steering tires "hunker down" when cornering. A double wishbone is usually pretty good at giving lots of negative camber on the outside wheel so when it folds over on itself, its closer to parallel with the road surface.
Also different tires of the same theoretical size have different profiles on the corner and stiffness in the belts which may or may not hold in that "center bulge" you're suffering.
Originally Posted By: badtlc
It sounds like type of tire on the same car can make a difference. Does anyone have any idea what the differences in tire construction would be that would allow this different tread wear at same PSIs?
There is no "one size fits all" answer for "correct" tire pressures.
Not everything you read on the internet is true.
To answer your question:
Tire size; ply rating; Load Rating; LT or P-metric; winter, summer, all-season; highway, all-terrain, off-road; bias-ply, radial or run-flat; etc.; etc.
The point is there are almost an infinite number of variables that affect how higher than recommended tire pressures will work on your particular vehicle.
One thing that would help reduce the confusion would be to cite increased tire pressures as a % above recommended pressure rather than a psi amount. For example, 6 psi in a low-profile highway tire would, probably, show much different results than 6 psi in a large truck tire.
The auto makers invest a lot of research into determining the recommended tire pressures and recommended tire sizes for their new cars. These sizes and pressures, indicated on the door jambs of every new car, can be viewed as the best compromise to meet all design criteria which could include, but are not limited, to the following (and not necessarily in this order)under average use conditions:
- Safety
- Gas mileage
- Ride comfort
- Load carrying ability
- Vehicle handling
- Tire wear
Adjusting the recommended tire pressures, either up or down, will affect the balance of performance criteria recommended by the manufacturer. This isn't necessarily a bad thing. If, for instance, you always traveled with several passengers and cargo, then you might be better off increasing the tire pressure to better handle the increased load. For better gas mileage, you might be better off increasing the recommended pressures in an attempt to decrease rolling resistance. The price you pay, however, is decreased performance in other areas like tire wear, braking performance and handling.
In your case badtlc, it seems you have done all the experimentation necessary to clearly determine that if the tire wear you are currently experiencing with your +6psi pressures is unacceptable, you should clearly reduce your pressures.
Sure, there can be general guidelines for tire pressures, but it impossible to say with any certainty what pressures are ideal for your situation without some specific data. Sounds like you have collected that data, so go ahead and act on it - reduce your pressures.
It sounds like type of tire on the same car can make a difference. Does anyone have any idea what the differences in tire construction would be that would allow this different tread wear at same PSIs?
There is no "one size fits all" answer for "correct" tire pressures.
Not everything you read on the internet is true.
To answer your question:
Tire size; ply rating; Load Rating; LT or P-metric; winter, summer, all-season; highway, all-terrain, off-road; bias-ply, radial or run-flat; etc.; etc.
The point is there are almost an infinite number of variables that affect how higher than recommended tire pressures will work on your particular vehicle.
One thing that would help reduce the confusion would be to cite increased tire pressures as a % above recommended pressure rather than a psi amount. For example, 6 psi in a low-profile highway tire would, probably, show much different results than 6 psi in a large truck tire.
The auto makers invest a lot of research into determining the recommended tire pressures and recommended tire sizes for their new cars. These sizes and pressures, indicated on the door jambs of every new car, can be viewed as the best compromise to meet all design criteria which could include, but are not limited, to the following (and not necessarily in this order)under average use conditions:
- Safety
- Gas mileage
- Ride comfort
- Load carrying ability
- Vehicle handling
- Tire wear
Adjusting the recommended tire pressures, either up or down, will affect the balance of performance criteria recommended by the manufacturer. This isn't necessarily a bad thing. If, for instance, you always traveled with several passengers and cargo, then you might be better off increasing the tire pressure to better handle the increased load. For better gas mileage, you might be better off increasing the recommended pressures in an attempt to decrease rolling resistance. The price you pay, however, is decreased performance in other areas like tire wear, braking performance and handling.
In your case badtlc, it seems you have done all the experimentation necessary to clearly determine that if the tire wear you are currently experiencing with your +6psi pressures is unacceptable, you should clearly reduce your pressures.
Sure, there can be general guidelines for tire pressures, but it impossible to say with any certainty what pressures are ideal for your situation without some specific data. Sounds like you have collected that data, so go ahead and act on it - reduce your pressures.
From a Nokian FAQ:
My tyres wear more in the middle than at the sides. Do I have incorrect inflation pressures, or why does this happen?
Traction tyres normally wear more in the middle than at the sides and free-rolling tyres wear more at the sides. The best way to even out the wear and to get the best possible driving results from your tyres is to rotate the positions of the tyres between the front and rear axles after every 8,000-10,000 km (5,000-6,000 miles).
My tyres wear more in the middle than at the sides. Do I have incorrect inflation pressures, or why does this happen?
Traction tyres normally wear more in the middle than at the sides and free-rolling tyres wear more at the sides. The best way to even out the wear and to get the best possible driving results from your tyres is to rotate the positions of the tyres between the front and rear axles after every 8,000-10,000 km (5,000-6,000 miles).
OP...
Different cars, different tires....different weight loads, different driving environments/circumstances, different driving styles...etc, etc....
Just a case here of you not believing your lying eyes...like anything/everything on the web, you can't base your behavior solely on others' experiences...
Kitacam's door jamb specs are 29-all around...after adding 2psi for 1 month at a time I've settled on 35 and am getting even wear.
Different cars, different tires....different weight loads, different driving environments/circumstances, different driving styles...etc, etc....
Just a case here of you not believing your lying eyes...like anything/everything on the web, you can't base your behavior solely on others' experiences...
Kitacam's door jamb specs are 29-all around...after adding 2psi for 1 month at a time I've settled on 35 and am getting even wear.
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OVERKILL
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You are assuming the accounts of the people you read about on the Internet are factual. Many of them probably aren't.
People are idiots. There are people out there claiming perfect tread-wear while they hyper-mile their Civic running 20psi over the placard and are endangering the lives of everybody around them by greatly increasing their braking distance and reducing their car's footprint in the name of "fuel economy".
Everybody is selling something. Odds are that if it doesn't jive with what makes sense, it is a steaming pile of "experience" they are trying to get you to swallow.
People are idiots. There are people out there claiming perfect tread-wear while they hyper-mile their Civic running 20psi over the placard and are endangering the lives of everybody around them by greatly increasing their braking distance and reducing their car's footprint in the name of "fuel economy".
Everybody is selling something. Odds are that if it doesn't jive with what makes sense, it is a steaming pile of "experience" they are trying to get you to swallow.
I run 40 psi and have never noticed uneven treadwear.
*shrug*
*shrug*
Originally Posted By: badtlc
....... Does anyone have any idea what the differences in tire construction would be that would allow this different tread wear at same PSIs?.....
Yes, and those folks are called tire engineers - and the kinds of things that can be manipulated to change the wear picture are internal to the tire and not the sort of thing written on the sidewall.
As many of you know, I am not a fan of using inflation pressure much above the vehicle placard pressure.
But in all honestly, there are things that cause tire wear that have much greater affect than inflation pressure.
For example, steer tires tend to wear in the shoulders (for obvious reasons0 while drive tires tend to wear in the center. This affect can be seen in rear wheel drive vehicles where these 2 things are separate. FWD cars ought to get even wear on the front and rears.
- BUT -
If a FWD turns a lot of corners or drives on twisty roads, this can cause shoulder wear to overwhelm what I wrote above - AND - going to higher inflation pressure would counteract that wear. So in theory, it's quite possible to get even wear with those high inflation pressures.
That's not the only scenario, but you get the idea. Tire wear is complex and has many variables.
....... Does anyone have any idea what the differences in tire construction would be that would allow this different tread wear at same PSIs?.....
Yes, and those folks are called tire engineers - and the kinds of things that can be manipulated to change the wear picture are internal to the tire and not the sort of thing written on the sidewall.
As many of you know, I am not a fan of using inflation pressure much above the vehicle placard pressure.
But in all honestly, there are things that cause tire wear that have much greater affect than inflation pressure.
For example, steer tires tend to wear in the shoulders (for obvious reasons0 while drive tires tend to wear in the center. This affect can be seen in rear wheel drive vehicles where these 2 things are separate. FWD cars ought to get even wear on the front and rears.
- BUT -
If a FWD turns a lot of corners or drives on twisty roads, this can cause shoulder wear to overwhelm what I wrote above - AND - going to higher inflation pressure would counteract that wear. So in theory, it's quite possible to get even wear with those high inflation pressures.
That's not the only scenario, but you get the idea. Tire wear is complex and has many variables.
Originally Posted By: CapriRacer
For example, steer tires tend to wear in the shoulders (for obvious reasons0 while drive tires tend to wear in the center. This affect can be seen in rear wheel drive vehicles where these 2 things are separate.
I agree. Even the fronts get 4 PSI more than door placard and the rears get 2 PSI above placard, the front and rear wear rate are exactly what you state.
That why tire rotation will even out the wear for all corners.
For example, steer tires tend to wear in the shoulders (for obvious reasons0 while drive tires tend to wear in the center. This affect can be seen in rear wheel drive vehicles where these 2 things are separate.
I agree. Even the fronts get 4 PSI more than door placard and the rears get 2 PSI above placard, the front and rear wear rate are exactly what you state.
That why tire rotation will even out the wear for all corners.
I have always rotated tires every 7,500 miles on my FWD vehicles. It never made a difference. I have always had to end up going back to the placard PSIs due to the uneven wear.
It is amazing to see how drastic the differences are between people even with the same cars and tires.
It is amazing to see how drastic the differences are between people even with the same cars and tires.
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Each rotation I do is 1.5x miles over the previous so that the pair on the rear (that were previously on the front) will have more miles with less wear (FWD cars)....that gives the tires even wear/tire life so I can replace all 4 at the same time.
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Originally Posted By: KitaCam
Each rotation I do is 1.5x miles over the previous so that the pair on the rear (that were previously on the front) will have more miles with less wear (FWD cars)[While the tires on the front get more miles with more wear]....that gives the tires even wear/tire life so I can replace all 4 at the same time.
Your strategy doesn't make any sense. Think about it for a second.
Let's say, for sake of discussion, that the front tires wear twice as much as the rear tires.
And let's say, again for sake of discussion, that we are rotating tires every 5,000 miles.
Finally, let's say we are starting with a new set of tires.
When the tires are first put on the car, wear is as follows:
Front: 0 x 2 = 0 equivalent wear miles
Rear: 0 x 1 = 0 equivalent wear miles
After 5,000 miles, wear is as follows:
Front: 5,000 x 2 = 10,000 equivalent wear miles
Rear: 5,000 x 1 = 5,000 equivalent wear miles
Rotate the tires Front to Rear, so wear is as follows:
Front: 5,000 x 1 = 5,000 equivalent wear miles
Rear: 5,000 x 2 = 10,000 equivalent wear miles
Drive 5,000 miles, so wear is as follows:
Front: 5,000 + (5,000 x 2) 10,000 = 15,000 equivalent wear miles
Rear: 10,000 + (5,000 x 1) 5,000 = 15,000 equivalent wear miles.
All even steven after 10,000 miles of driving.
Have a nice day.
Each rotation I do is 1.5x miles over the previous so that the pair on the rear (that were previously on the front) will have more miles with less wear (FWD cars)[While the tires on the front get more miles with more wear]....that gives the tires even wear/tire life so I can replace all 4 at the same time.
Your strategy doesn't make any sense. Think about it for a second.
Let's say, for sake of discussion, that the front tires wear twice as much as the rear tires.
And let's say, again for sake of discussion, that we are rotating tires every 5,000 miles.
Finally, let's say we are starting with a new set of tires.
When the tires are first put on the car, wear is as follows:
Front: 0 x 2 = 0 equivalent wear miles
Rear: 0 x 1 = 0 equivalent wear miles
After 5,000 miles, wear is as follows:
Front: 5,000 x 2 = 10,000 equivalent wear miles
Rear: 5,000 x 1 = 5,000 equivalent wear miles
Rotate the tires Front to Rear, so wear is as follows:
Front: 5,000 x 1 = 5,000 equivalent wear miles
Rear: 5,000 x 2 = 10,000 equivalent wear miles
Drive 5,000 miles, so wear is as follows:
Front: 5,000 + (5,000 x 2) 10,000 = 15,000 equivalent wear miles
Rear: 10,000 + (5,000 x 1) 5,000 = 15,000 equivalent wear miles.
All even steven after 10,000 miles of driving.
Have a nice day.
Thanks Gaijin....but I don't do math...
I practice empirical observation and have always had even wear rotating tires this way (typical rotations of apprx. 6k/9k/12k to end of tread, usually @ 30-33k miles) and all 4 have always needed to be replaced at the same time...maybe it's just the tires/cars I had driven over the past 15 years (Altimas) and the way I drive...of course it can always change with the KitaCam...
I practice empirical observation and have always had even wear rotating tires this way (typical rotations of apprx. 6k/9k/12k to end of tread, usually @ 30-33k miles) and all 4 have always needed to be replaced at the same time...maybe it's just the tires/cars I had driven over the past 15 years (Altimas) and the way I drive...of course it can always change with the KitaCam...
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Originally Posted By: KitaCam
Thanks Gaijin....but I don't do math...
I'll remember that
Thanks Gaijin....but I don't do math...
I'll remember that
Originally Posted By: gaijinnv
Originally Posted By: KitaCam
Thanks Gaijin....but I don't do math...
I'll remember that
Yup...as long as it works...
Originally Posted By: KitaCam
Thanks Gaijin....but I don't do math...
I'll remember that
Yup...as long as it works...
math doesnt matter if you just pull the assumption that the front is going to wear twice as fast as the back.. out of midair.
observation doesnt lie.
maybe kitacam's car is wearing the front at 1.5x the back?
you can math out every possible scenario.. but just looking and measuring the tires with a depth gauge wont lie..
Originally Posted By: gaijinnv
Originally Posted By: KitaCam
Each rotation I do is 1.5x miles over the previous so that the pair on the rear (that were previously on the front) will have more miles with less wear (FWD cars)[While the tires on the front get more miles with more wear]....that gives the tires even wear/tire life so I can replace all 4 at the same time.
Your strategy doesn't make any sense. Think about it for a second.
Let's say, for sake of discussion, that the front tires wear twice as much as the rear tires.
And let's say, again for sake of discussion, that we are rotating tires every 5,000 miles.
Finally, let's say we are starting with a new set of tires.
When the tires are first put on the car, wear is as follows:
Front: 0 x 2 = 0 equivalent wear miles
Rear: 0 x 1 = 0 equivalent wear miles
After 5,000 miles, wear is as follows:
Front: 5,000 x 2 = 10,000 equivalent wear miles
Rear: 5,000 x 1 = 5,000 equivalent wear miles
Rotate the tires Front to Rear, so wear is as follows:
Front: 5,000 x 1 = 5,000 equivalent wear miles
Rear: 5,000 x 2 = 10,000 equivalent wear miles
Drive 5,000 miles, so wear is as follows:
Front: 5,000 + (5,000 x 2) 10,000 = 15,000 equivalent wear miles
Rear: 10,000 + (5,000 x 1) 5,000 = 15,000 equivalent wear miles.
All even steven after 10,000 miles of driving.
Have a nice day.
observation doesnt lie.
maybe kitacam's car is wearing the front at 1.5x the back?
you can math out every possible scenario.. but just looking and measuring the tires with a depth gauge wont lie..
Originally Posted By: gaijinnv
Originally Posted By: KitaCam
Each rotation I do is 1.5x miles over the previous so that the pair on the rear (that were previously on the front) will have more miles with less wear (FWD cars)[While the tires on the front get more miles with more wear]....that gives the tires even wear/tire life so I can replace all 4 at the same time.
Your strategy doesn't make any sense. Think about it for a second.
Let's say, for sake of discussion, that the front tires wear twice as much as the rear tires.
And let's say, again for sake of discussion, that we are rotating tires every 5,000 miles.
Finally, let's say we are starting with a new set of tires.
When the tires are first put on the car, wear is as follows:
Front: 0 x 2 = 0 equivalent wear miles
Rear: 0 x 1 = 0 equivalent wear miles
After 5,000 miles, wear is as follows:
Front: 5,000 x 2 = 10,000 equivalent wear miles
Rear: 5,000 x 1 = 5,000 equivalent wear miles
Rotate the tires Front to Rear, so wear is as follows:
Front: 5,000 x 1 = 5,000 equivalent wear miles
Rear: 5,000 x 2 = 10,000 equivalent wear miles
Drive 5,000 miles, so wear is as follows:
Front: 5,000 + (5,000 x 2) 10,000 = 15,000 equivalent wear miles
Rear: 10,000 + (5,000 x 1) 5,000 = 15,000 equivalent wear miles.
All even steven after 10,000 miles of driving.
Have a nice day.
Originally Posted By: Rand
math doesnt matter if you just pull the assumption that the front is going to wear twice as fast as the back.. out of midair.
observation doesnt lie.
maybe kitacam's car is wearing the front at 1.5x the back?
you can math out every possible scenario.. but just looking and measuring the tires with a depth gauge wont lie..
The beauty of the math is that it clearly shows that IT DOES NOT MATTER how much faster the front may wear than the back. It can be the same, it can be 3x faster, 1.5x faster, 2.3456789x faster ... as long as you rotate after the same number of miles, after 2 driving cycles, the wear is the same front to rear.
The math does not lie.
math doesnt matter if you just pull the assumption that the front is going to wear twice as fast as the back.. out of midair.
observation doesnt lie.
maybe kitacam's car is wearing the front at 1.5x the back?
you can math out every possible scenario.. but just looking and measuring the tires with a depth gauge wont lie..
The beauty of the math is that it clearly shows that IT DOES NOT MATTER how much faster the front may wear than the back. It can be the same, it can be 3x faster, 1.5x faster, 2.3456789x faster ... as long as you rotate after the same number of miles, after 2 driving cycles, the wear is the same front to rear.
The math does not lie.
The math does not lie as long as your assumptions are reasonable and reflect the real world. For example, if the mileage vs tread depth graph is not linear but rather exponential (or asymptotic), then the wear will no longer be the same.
Now you might ask why the graph would be non-linear? It could be by the design e.g. different gradation of tire compound on the surface. Or it could be because as tire wears out, it rotates faster for the same amount of mileage which causes it to wear out even more.
Now you might ask why the graph would be non-linear? It could be by the design e.g. different gradation of tire compound on the surface. Or it could be because as tire wears out, it rotates faster for the same amount of mileage which causes it to wear out even more.
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