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View Full Version : Camber or toe kills tires?



Kookz
02-10-2004, 04:02 AM
Yeah I know you all want to come in and repeat the mantra that camber doesn't kill tires, toe does. Well, they both do, of course. I just finally took the 45 seconds to calculate to what extent each kills tires...

1 degree of camber (positive or negative, doesn't matter) has the same effect (when driven in a perfectly straight line) as .872" of toe in (or out), assuming that the tires are inelastic. Now to what extent this is true under real world circumstances, I'd have to be a rubber engineer to calculate...but camber defenitely does cause tire wear.

Dorifto_PG
02-10-2004, 04:12 AM
[clapclapclapclapclapclapclap]

But lest you forget a "perfect" alignment for Mrs. Barbara Smith, 57, driving her stock 240sx would be an aligment from hell for me. I would put so much excessive wear on the outer shoulder of those tires. Like my old S14! http://forums.freshalloy.com/images/graemlins/tongue.gif

As for REAR camber... tires should not last long enough to wear down naturally due to camber settings. Or toe for that matter.

Conclusion? post your calculations for all the posuers who want a "drfit car look" with 5 degrees of camber (wtf^^ mate?). Running 2.5-3 degrees of camber should wear evenly. otherwise you drive like too big of a pansy. http://forums.freshalloy.com/images/graemlins/blush.gif YOU'RE A PANSY BJones! PANSY! http://forums.freshalloy.com/images/graemlins/laugh.gif "oh look at me, I'm being badass, but being nice. Herr herr herr. Or should I say: Being candyass, but being pansy!" http://forums.freshalloy.com/images/graemlins/rolleyes1.gif

Kookz
02-10-2004, 04:17 AM
Haha. It's just cause everyone always comes in with "camber doesn't kill tires, toe does". Well, camber DOES kill tires. Just like toe.

Dorifto_PG
02-10-2004, 04:19 AM
Camber doesn't kill tires. I kill tires.

asad
02-10-2004, 08:04 AM
Haha. It's just cause everyone always comes in with "camber doesn't kill tires, toe does". Well, camber DOES kill tires. Just like toe.



You're forgetting the fact that when driving in a straight line, camber doesn't cause tires to scrub against the road. Toe does. 1 degree of camber with no toe, and the tire can still roll along just fine. 1 degree of toe, and you get more wear because you're pushing the tire, in effect, sideways a little.

Asad

ThonG
02-10-2004, 08:30 AM
Kookz, you drive too damn hard, thats why you kill tires.

my fm901's have a whole nother season left and im running -2.5 front and -3 back, no excessive wear on either side.

Thon

jimc-s13
02-10-2004, 09:13 AM
Not sure if you're serious or not, but there is no way possible that 1 degree of camber is going to cause as much tire wear as almost a full inch of toe. That much toe would not only make the car nearly impossible to drive, but would cause so much scrub I can't imagine the tires would last more than 5000 miles.

The best example I've heard is to take a roll of toilet paper, put piece of dowel rod through it so you can roll it like a tire, and roll it on a piece of sandpaper with some camber. Notice that it wears a little unevenly, but not much. Now roll it with some toe but no camber, and notice the greatly increased but pretty even wear. Then, roll it with both toe and camber, and notice the high rate of uneven wear.

IOW, toe kills the tires, and if you have tire-killing toe, camber will help your tires wear out faster and unevenly.

moorefire
02-10-2004, 09:38 AM
I think he ment .872 degrees.

I don't think you can measure toe as a distance unless you specify how far you are from the steering axis.

"Camber dosen't kill tires, I kill tires."

Thats [censored] hilarious http://forums.freshalloy.com/images/graemlins/grin.gif

Kim_Jong_Il
02-10-2004, 10:35 AM
Toe massacres tires and makes their children cry. I bent a tie rod pretty bad on an S13 years ago (thing looked like a damn shifter). That day I drove about 25 or 30 miles with it like that. Felt like I was a NASCAR driver, made great left turns, just let go and I would track and oval no problem. But going straight it howled like a cat in heat and was twitchy as all hell.

When I pulled off the tire that night to replace the tie rod the tire was in really bad shape. It went from being practically new to on the verge of balding death in a matter of hours.

Remember the moral: "This is your tire... This your tire on too much toe"

Camber on the other hand, pretty bad too, but I used to run about -2 or so (not much really) on the rear of my S13. Didn't rotate tires since I was lazy, would typically get about 6 months out of the rear. But that could lean more towards my driving habits of the time (and I guess now somewhat) being at fault. Insides would get eaten up pretty bad.

Thx247
02-10-2004, 03:14 PM
Just like everyone else, I've heard toe kills tires more than camber does. Based on my experinces I'd have to believe it. I can run -2 degrees up front and in the rear and basically get even wear on Azenis. If I run anything less the shoulder starts to smooth out and eventually I have a half slick tire.

For the street I can see the usefullness of getting decent wear out of tires (align for road crown and everything...) but for track I'm just running what works.

Kookz
02-10-2004, 04:37 PM
Like I said, this is based on the tires being inelastic, which is not exactly true.


I think he ment .872 degrees.

I don't think you can measure toe as a distance unless you specify how far you are from the steering axis.


1" toe in means that the front of the tires are 1" closer together than the rear, check your FSM, it's in there.



You're forgetting the fact that when driving in a straight line, camber doesn't cause tires to scrub against the road.

Oh but it does! Tilt a tire at an angle and imagine the line a point on the tire makes when it hits the road. When the tire first hits (at the front of the contact patch), it's closer to the center of the car than it is when it's in the middle of the contact patch. So, it moves out, then returns to a spot closer to the middle. So really, it looks like this:
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Not sure if you're serious or not, but there is no way possible that 1 degree of camber is going to cause as much tire wear as almost a full inch of toe.

Like I said, that's assuming the tires are inelastic, and I would have to have a much better knowledge of rubber to know exactly how much it would actually hold true. The difference between the 2 is that the imaginary point on the cambered tire only moves half the distance to the side, then that distance back in. If it's elastic enough, it may be able to just deform out and back without actually sliding sideways on the surface. This obviously happens to a certain extent and does explain why 1 degree of camber doesn't cause the issues that .872" of toe does, hence why I said assuming inelasticity, etc.

Thx247
02-10-2004, 06:53 PM
Holy cow an full inch of toe? Those tires wouldn't last very long at all. The only good thing about running that much toe would be road head, your hands would be free to do other things than steer the car...cause a car with that much toe is going STRAIGHT.

DudeYourSoooJDM
02-10-2004, 07:26 PM
I run -2 camber and 0 toe.....I have gone through about 15 sets of rear tires in my 240's lifetime.

If I drive normally, I see normal wear.

Drifting........My tires get murdered on the inside, but still have decent tread on the outsides.

Dorifto_PG
02-10-2004, 07:28 PM
Drifting........My tires get murdered on the inside, but still have decent tread on the outsides.


Because you aren;t going fast enough poosay. http://forums.freshalloy.com/images/graemlins/laugh.gif

DudeYourSoooJDM
02-10-2004, 07:30 PM
joo trippen.....at least top of 2nd 90 percent of time. http://forums.freshalloy.com/images/graemlins/grin.gif

Dorifto_PG
02-10-2004, 07:35 PM
joo trippen.....at least top of 2nd 90 percent of time. http://forums.freshalloy.com/images/graemlins/grin.gif


Exactly. With that car and that engine it should eb mid-top 3rd!!!!!!!!!!!! http://forums.freshalloy.com/images/graemlins/mad.gif http://forums.freshalloy.com/images/graemlins/tongue.gif

Wiisass
02-10-2004, 07:48 PM
Using 1" of toe the way Kookz is talking would give you 1.15 degrees toe in. That's using 25" for the diameter of the tire and 0.5" differnce from front to back on each side.

Kookz, what kind of calculations did you do to come up with this stuff?

Tim

RDM_II
02-10-2004, 08:53 PM
Holy cow an full inch of toe? Those tires wouldn't last very long at all. The only good thing about running that much toe would be road head, your hands would be free to do other things than steer the car...cause a car with that much toe is going STRAIGHT.



Actually it won't. I just played with my alignment and left the toe way off until the next day (got cold and dark outside), I measured it from tire sidewall across to the other, from the front edge to the rear edge was a half inch difference. The car drove CRAZY, like a HICAS car with the tie rod ends broken off the rack. It jerked back and forth between lanes and would barely track straight through a turn. It was far from cool. I had to drive 20mph just to keep from clipping other cars. My lesson= Toe is bad. Toe must be stopped. In our lifetime, before I kill somebody.

matts13
02-10-2004, 09:10 PM
i want to see this so called math you used to come up with this info

Mav1178
02-10-2004, 10:22 PM
Actually it won't. I just played with my alignment and left the toe way off until the next day (got cold and dark outside), I measured it from tire sidewall across to the other, from the front edge to the rear edge was a half inch difference. The car drove CRAZY, like a HICAS car with the tie rod ends broken off the rack. It jerked back and forth between lanes and would barely track straight through a turn. It was far from cool. I had to drive 20mph just to keep from clipping other cars. My lesson= Toe is bad. Toe must be stopped. In our lifetime, before I kill somebody.



Toe helps a car's entry and exit behavior when negotiating turns.

I for one, am happy with toe. In the proper amount, of course. Too little/much of a certain alignment spec would make the car unpredictable.

-alex

Kookz
02-11-2004, 12:33 AM
I just want to start by saying that what I said was that this was the case assuming the tires were inelastic, not a real life scenario. As someone who runs -3.5 degrees of camber up front with 0 toe, I know that real life and this calculation are very very different, I just did it for fun at 6am.



i want to see this so called math you used to come up with this info

Really easy stuff. Our tires are ~25" diameter.

Draw a right triangle with a 1 degree angle at the top and a hypotenuse of 12.5 (the radius of the tire). 12.5*sin(1)*(c)= the distance that the tire moves out during the time it's on the ground.

c = length of the contact patch/25, because the tire is obviously not touching the ground the for 25", but really just a small portion. However, we don't need to know or include this because it cancels later on.

Anyway, 12.5*sin(1)=.218". That's the distance it moves out, then it has to move back in the same distance. 2*.218=.436" This is the part where real world is different from toe, as the displacement is 0, but the abs. val. of the displacement is .436". Meaning...the tire can deform for .218" a lot easier than .436" in one direction.

So if each tire is toed in .436", that's the .872". The displacement for a point during toe would be .872*(c), but leaving out c simplifies both calculations since we don't know the length of the contact patch.

I didn't mean this to be "You'll wear the same with 1 degree of camber as with .872" of toe", I just meant it to show that camber does cause tire wear.

The deflection that is the difference between camber and toe (mentioned above) causes heat in tires. Feel the inside of your tires with neg. camber, and they're going to be HOT.

Highway driving is very hard on non-zero alignments...save your good tires for the twisties.

Salty_X
02-11-2004, 12:52 AM
Highway driving is very hard on non-zero alignments...save your good tires for the twisties.


Non-zero camber or toe? Or both? http://forums.freshalloy.com/images/graemlins/confused.gif

Kookz
02-11-2004, 01:06 AM
Both.