+1,000 what Drew said! LOL!
Rotating Directional Tires.
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Originally Posted By: benjamming
Any harm to the internal tire structure of a directional tire rotating the wrong way?
No. Directional tires - and asymmterical tires , too - do NOT have different structures. It's the tread pattern that is different. So there is no harm done to the structure by rotating in the wrong direction - or for mounting an asymetrical tire "inside out".
Any harm to the internal tire structure of a directional tire rotating the wrong way?
No. Directional tires - and asymmterical tires , too - do NOT have different structures. It's the tread pattern that is different. So there is no harm done to the structure by rotating in the wrong direction - or for mounting an asymetrical tire "inside out".
Originally Posted By: Hokiefyd
Originally Posted By: CapriRacer
Yes, the only property affected by having a directional tire rotate the wrong direction is wet traction. Grip and wear are unaffected.
Wet traction or hydroplane resistance?
First, wet traction and hydroplaning resistance are difficult to separate. But you can test a tire's wet grip by keeping the speed low, the water depth low, and the tread depth high. With those conditions, hydroplaning is a very small component compared to the grip between the rubber and the road.
Needless to say, substantially increasing the speed, substantially increasing the water depth, and a well worn tire, hydroplaning resistance is greatly affected. But, again, the difference between rotating one direction as opposed to the other direction results in only a small change.
Originally Posted By: CapriRacer
Yes, the only property affected by having a directional tire rotate the wrong direction is wet traction. Grip and wear are unaffected.
Wet traction or hydroplane resistance?
First, wet traction and hydroplaning resistance are difficult to separate. But you can test a tire's wet grip by keeping the speed low, the water depth low, and the tread depth high. With those conditions, hydroplaning is a very small component compared to the grip between the rubber and the road.
Needless to say, substantially increasing the speed, substantially increasing the water depth, and a well worn tire, hydroplaning resistance is greatly affected. But, again, the difference between rotating one direction as opposed to the other direction results in only a small change.
Originally Posted By: Astro14
..something that drastically (and 10% is drastic) degrades it...
Now hold on a second - you're saying that reducing a vehicle's ultimate grip from, say, 0.90 g to 0.81 g, or having the onset of hydroplaning move from 67 mph to 60 mph, is 'drastic'? You and I have different definitions of the word 'drastic', friend.
Substantial, yes. Drastic, I don't think so.
..something that drastically (and 10% is drastic) degrades it...
Now hold on a second - you're saying that reducing a vehicle's ultimate grip from, say, 0.90 g to 0.81 g, or having the onset of hydroplaning move from 67 mph to 60 mph, is 'drastic'? You and I have different definitions of the word 'drastic', friend.
Substantial, yes. Drastic, I don't think so.
Originally Posted By: CivicFan
But if you read the TireRack article, you will see that there was no compromise in safety.
Again, I think that's a dangerous conclusion, and not one they came up with. They noted in the article, if one reads the full text, that their setup replicates very smooth roadways with minimal water sheeting. Their setup does not replicate rutted roads, standing water, puddles, etc.
I think you can say that there is no compromise in safety when you mount directional tires backwards if and only if you don't need to use the directionality of the tire's tread.
I understand and appreciate the mechanic's point. I think his advice just needs to come with a few caveats, a few "if and only ifs".
But if you read the TireRack article, you will see that there was no compromise in safety.
Again, I think that's a dangerous conclusion, and not one they came up with. They noted in the article, if one reads the full text, that their setup replicates very smooth roadways with minimal water sheeting. Their setup does not replicate rutted roads, standing water, puddles, etc.
I think you can say that there is no compromise in safety when you mount directional tires backwards if and only if you don't need to use the directionality of the tire's tread.
I understand and appreciate the mechanic's point. I think his advice just needs to come with a few caveats, a few "if and only ifs".
Originally Posted By: leeharvey418
Tire Rack tested the theory that directional tires are substantially worse in the rain when run 'backwards'. In a nutshell, as long as the pavement isn't up to the point where some non-directional tires would begin to hydroplane anyway, there's practically no difference in wet traction with respect to rotation direction.
Thanks. That confirms what I posted in the original post with the clarification of the need for lower speed in wet weather.
This will give some food for thought for the conventional wisdom.
Tire Rack tested the theory that directional tires are substantially worse in the rain when run 'backwards'. In a nutshell, as long as the pavement isn't up to the point where some non-directional tires would begin to hydroplane anyway, there's practically no difference in wet traction with respect to rotation direction.
Thanks. That confirms what I posted in the original post with the clarification of the need for lower speed in wet weather.
This will give some food for thought for the conventional wisdom.
Originally Posted By: CivicFan
the need for lower speed in wet weather.
Lower speed in wet weather is Common Sense...
But, Reversed mounting of directional or Asymmetric tires in Virginia will fail state vehicle inspections.
Jim
the need for lower speed in wet weather.
Lower speed in wet weather is Common Sense...
But, Reversed mounting of directional or Asymmetric tires in Virginia will fail state vehicle inspections.
Jim
The Tire Rack test may have also had something to do with the particular directional tire they tested - the Eagle F1 GS-D3 tread looks like it would usually have only two central ends of a groove in the contact patch at a time - the other grooves would be able to channel the water either forward or backward out of the contact patch, so except for a couple of relatively small spots in the center of the contact patch, you're hardly ever pumping water toward the center with this tire like you would be with a shallower groove angle like you see on something like the Michelin Pilot Sport A/S.
Check out the picture of the GS-D3's contact patch from Car and Driver - you may note that most of the grooves are completely open from the front to the rear of the contact patch.
Check out the picture of the GS-D3's contact patch from Car and Driver - you may note that most of the grooves are completely open from the front to the rear of the contact patch.
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Originally Posted By: CapriRacer
Originally Posted By: benjamming
Any harm to the internal tire structure of a directional tire rotating the wrong way?
No. Directional tires - and asymmterical tires , too - do NOT have different structures. It's the tread pattern that is different. So there is no harm done to the structure by rotating in the wrong direction - or for mounting an asymetrical tire "inside out".
So, am I to take-away from this thread that I can open up my tire buying choices to include directional tires & ignore the arrows when rotating. I currently don't buy directional tires b/c something will cause the alignment to get all screwy during the tire's life & rotating helps me to extend the life of the tires.
Originally Posted By: benjamming
Any harm to the internal tire structure of a directional tire rotating the wrong way?
No. Directional tires - and asymmterical tires , too - do NOT have different structures. It's the tread pattern that is different. So there is no harm done to the structure by rotating in the wrong direction - or for mounting an asymetrical tire "inside out".
So, am I to take-away from this thread that I can open up my tire buying choices to include directional tires & ignore the arrows when rotating. I currently don't buy directional tires b/c something will cause the alignment to get all screwy during the tire's life & rotating helps me to extend the life of the tires.
Originally Posted By: benjamming
So, am I to take-away from this thread that I can open up my tire buying choices to include directional tires & ignore the arrows when rotating. I currently don't buy directional tires b/c something will cause the alignment to get all screwy during the tire's life & rotating helps me to extend the life of the tires.
Rotate front to back...
So, am I to take-away from this thread that I can open up my tire buying choices to include directional tires & ignore the arrows when rotating. I currently don't buy directional tires b/c something will cause the alignment to get all screwy during the tire's life & rotating helps me to extend the life of the tires.
Rotate front to back...
Originally Posted By: leeharvey418
Originally Posted By: Astro14
..something that drastically (and 10% is drastic) degrades it...
Now hold on a second - you're saying that reducing a vehicle's ultimate grip from, say, 0.90 g to 0.81 g, or having the onset of hydroplaning move from 67 mph to 60 mph, is 'drastic'? You and I have different definitions of the word 'drastic', friend.
Substantial, yes. Drastic, I don't think so.
And of course that 10% difference is with new tires and maximum tread depth. As the tires wear that differential should decline.
The only reason to run directional tread backwards is when the tires are worn and you're rotating the tires to even up the tread wear. At that point I don't think it matters much.
Originally Posted By: Astro14
..something that drastically (and 10% is drastic) degrades it...
Now hold on a second - you're saying that reducing a vehicle's ultimate grip from, say, 0.90 g to 0.81 g, or having the onset of hydroplaning move from 67 mph to 60 mph, is 'drastic'? You and I have different definitions of the word 'drastic', friend.
Substantial, yes. Drastic, I don't think so.
And of course that 10% difference is with new tires and maximum tread depth. As the tires wear that differential should decline.
The only reason to run directional tread backwards is when the tires are worn and you're rotating the tires to even up the tread wear. At that point I don't think it matters much.
I'd run directional in reverse only in dry weather that will guarantee not to rain, and when they are still with high trend depth.
A near bald directional in reverse in wet weather is trouble in the making.
A near bald directional in reverse in wet weather is trouble in the making.
Originally Posted By: PandaBear
I'd run directional in reverse only in dry weather that will guarantee not to rain, and when they are still with high trend depth.
A near bald directional in reverse in wet weather is trouble in the making.
True. Near bald is trouble in the making anyway
I'd run directional in reverse only in dry weather that will guarantee not to rain, and when they are still with high trend depth.
A near bald directional in reverse in wet weather is trouble in the making.
True. Near bald is trouble in the making anyway
Originally Posted By: CATERHAM
And of course that 10% difference is with new tires and maximum tread depth. As the tires wear that differential should decline.
Eh... I really have to question that assumption. When the tires are new, the 'groove volume' would be bigger, so that the water being displaced would have a less-restricted path to either the front or rear of the contact patch; not to mention the fact that a relatively thin film could be pushed into and contained in the grooves as the tire rolls past. Once the tire becomes worn, I would think the tread design elements would play a bigger role in expelling the water from the contact patch.
And of course that 10% difference is with new tires and maximum tread depth. As the tires wear that differential should decline.
Eh... I really have to question that assumption. When the tires are new, the 'groove volume' would be bigger, so that the water being displaced would have a less-restricted path to either the front or rear of the contact patch; not to mention the fact that a relatively thin film could be pushed into and contained in the grooves as the tire rolls past. Once the tire becomes worn, I would think the tread design elements would play a bigger role in expelling the water from the contact patch.
Originally Posted By: CivicFan
Near bald is trouble in the making anyway
Amen, brother.
Near bald is trouble in the making anyway
Amen, brother.
Originally Posted By: leeharvey418
Originally Posted By: CivicFan
Near bald is trouble in the making anyway
Amen, brother.
Since racing and track days is my hobby I've had plenty of experience driving on slicks and on bald or near bald R compound tires at speed in the rain. I consider near bald as optimum even for street use as long as the rubber has not hardened too much with age. Full tread depth tires don't handle near as well as shallow treaded or their near bald counterparts. When it rains you slow down; what could be simpler.
The only use for tread that I have is for winter driving in snow and on other loose services.
Originally Posted By: CivicFan
Near bald is trouble in the making anyway
Amen, brother.
Since racing and track days is my hobby I've had plenty of experience driving on slicks and on bald or near bald R compound tires at speed in the rain. I consider near bald as optimum even for street use as long as the rubber has not hardened too much with age. Full tread depth tires don't handle near as well as shallow treaded or their near bald counterparts. When it rains you slow down; what could be simpler.
The only use for tread that I have is for winter driving in snow and on other loose services.
That's all well and good, but it doesn't hold a lot of water (no pun intended) with me when F1, back when they ran slicks in dry conditions, still ran treaded tires when it rained...
Originally Posted By: CATERHAM
The only reason to run directional tread backwards is when the tires are worn and you're rotating the tires to even up the tread wear. At that point I don't think it matters much.
A better reason is that you have a directional tire on your spare, and you need to use the spare on the "wrong" side of the car.
The only reason to run directional tread backwards is when the tires are worn and you're rotating the tires to even up the tread wear. At that point I don't think it matters much.
A better reason is that you have a directional tire on your spare, and you need to use the spare on the "wrong" side of the car.
F1 is back to running full slicks now and as always have both intermediate and full rain tires.
But you'll get better grip with slicks on a damp track than with treaded "inter's" and on a drying track they will change over to slicks long before the track is "dry".
The only advantage tread offers is increased resistance to hydroplanning at high speeds. At low speed there is no advantage.
I have found even driving during a downpour on bald tires, if you keep your speed under 50 mph you can avoid hydroplanning, and that's on wide low profile tires.
I don't live in the desert nevertheless I'd estimate that 99% of my driving is still on dry road. I therefore choose a tire that's optimized for the conditions I usually drive under. Rain is a none issue since all one needs to do is slow down to retain perfect control.
Winter driving on the otherhand is a whole different issue as I mentioned previously.
But you'll get better grip with slicks on a damp track than with treaded "inter's" and on a drying track they will change over to slicks long before the track is "dry".
The only advantage tread offers is increased resistance to hydroplanning at high speeds. At low speed there is no advantage.
I have found even driving during a downpour on bald tires, if you keep your speed under 50 mph you can avoid hydroplanning, and that's on wide low profile tires.
I don't live in the desert nevertheless I'd estimate that 99% of my driving is still on dry road. I therefore choose a tire that's optimized for the conditions I usually drive under. Rain is a none issue since all one needs to do is slow down to retain perfect control.
Winter driving on the otherhand is a whole different issue as I mentioned previously.
...and I have found that on nearly bald tires my vehicles tend to hydroplane at something far less than that I would call 'fast'. Not to mention that objective testing demonstrates that deeper tread is better at handling water than shallow tread.
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