I agree with you panda. I've always been told the front also cos you need to steer (even in a rear wheel) and brake from the front more.
Printable View
I agree with you panda. I've always been told the front also cos you need to steer (even in a rear wheel) and brake from the front more.
MICHELIN: When new tires are installed on the rear, it helps reduce the potential for your vehicle to fishtail or hydroplane in wet conditions.
Wikipedia: Hydroplaning or aquaplaning by a road vehicle occurs when a layer of water builds between the rubber tires of the vehicle and the road surface, leading to the loss of traction and thus preventing the vehicle from responding to control inputs such as steering, braking or accelerating. It becomes, in effect, an unpowered and unsteered sled.
So the three main dangers of hydroplaning are:
1: Poor acceleration
2: Poor breakng
3: Understeering
1. We know that a FWD drives with the front wheels, so in this case the drive wheels should have the new tyres, also, if a RWD has trouble taking off in the wet, then those tyres need to be replaced, not just dumped on the back!
2.Considering that a car's breaking system is front bias, whether FWD, RWD or AWD, it would be safer to have the new tyres on the front in wet conditions, to help stop quicker!
3. All, ALL cars steer with their front wheels other than maybe some pakistani car i've maybe never heard of (or preludes at low speed :p) so there is no defence there, they will all understeer as easily in the wet as each other!
I think michellin need to do some research and specify FWD, RWD a little clearer and maybe offer a different point of view, i would never have inferior tyres on the front of my car!
Beeeengooo... totally agree!!Quote:
Originally Posted by claymore
It's not that hard to jack ur car up every 5-10 000 k's and swap front and rear!
Gets a bit harder if you only have one drive wheel and directional tyres though :)
One drive wheel? Get your differential fixed!Quote:
Originally Posted by Kiz_EG6
An argument can be made that rotating tyres actually increases overall tyre wear. It goes like this; As a new tyre wears when fitted to a particular corner of the car, it wears according to the particular characteristics of the suspension on that corner. This includes static camber angle and the degree to which that suspenion gains camber with suspension defelection. When new the tyre's tread will not match the characteristics of the wear that will occur on the suspension to which it's fitted, it will have areas where the contact patch loading is more heavily loaded and areas where less heavily loaded (typically more loaded on the inner part of the contact patch due to neg camber).
The new tyre will be 'flat' across the tread, but is likely to wear more on one side of the tread than the other according to static and dynamic camber angles seen in service. When new the contact patch will be more heavily loaded on one side than the other, and will tend to wear more on the more heavily loaded side.
As it wears in to the suspension this difference in loading in different areas of the contact patch will even out as rubber wears away until the loading is more equal across the contact patch, but the tyre will go through an initial period of 'accelerated' wear until this state is acheived.
If we now move that 'worn in' tyre to a different corner with a different suspension characteristic it will go through another period of 'wearing in' where the wear rate in some part of the tread will be faster than it will be once the tyre has worn in to the characteristics of the 'new' suspension.
So, when we rotate tyres we may spread the totality of wear more evenly over all of the four tyres, but each individual tyre will tend to wear more quickly. This may not be a big difference, but in principle it exists.
A non LSD FWD or RWD (unless you are a grandma driver) will always wear out the drive wheel quicker than the other, whereas, an LSD equipped vehicle wears far more evenly!! Burnouts cause this problem even worse!!Quote:
Originally Posted by JohnL
I understand what you are saying about the camber wear, but if you have a correct suspension/camber setup and correct PSI in ur tyres for your driving style, then the camber wear should not generally be noticeable (I had 1.5 degree to the negative on the back of my EG and 1.75 to the negative on the front, and the tyre wear was even across the tread) so though this is a factor, i would be more concerned with uneven wear front:rear.
i would of istantly put new tyres in the front
logicially
I've outgrown doing burnouts! Having said that, when on the rare occasion I unintentionally do one, or succumb to temptation and sneakily do one (just a small one, not great clouds of smoke!), both front wheels tend to spin more or less equally, so long as I'm not attempting to steer at the same time. This is more or less typical for front drivers (even with open differentials) because the torque reactions are longitudinal not lateral. So, respectfully I have to disagree.Quote:
Originally Posted by Kiz_EG6
For a typical front engined rear driver with a live rear axle; if the engine rotates clockwise as viewed from the front (typical), then the engine's torque attempts to lift the chassis on the left side and lower it on the right (i.e the engine torque attempts to rotate the whole chassis around the crank axis in the opposite direction to crank rotation), but at the differential the crown wheel will try to 'climb' the pinion and lift the right side of the axle in the same direction to drive shaft rotation (same as crank rotation).
This is why you so often see rear drivers 'light up' the right rear. The right rear spring loads up and the left rear spring unloads, but, the right rear wheel gets light, left wheel gets heavy and the right wheel spins easily. This is a function of engine torque, and it overcomes any weight induced loadings, i.e. force (from torque) is transferred laterally along the axle housing from one side to the other, so even though the right rear spring becomes a bit more compressed and the left rear a bit more uncompressed, the right rear contact patch lightens and the left rear patch loads up.
A rear driver with an independant rear end is different; there is no lateral torque reaction at the rear wheels that is is independant of torque reaction into the chassis. There is a torque reaction into the chassis that lifts the chassis on the left side and lowers it on the right as above, and this loads up the right rear spring while unloading the left rear spring, but because the differential is solidly attached to the chassis and not the suspension this results in the left rear becoming lighter and being more likely to lose traction than the right rear.
This effect is not nearly as strong as the opposite effect with a live rear axle. A live rear axle suffers a lot more from torque reaction and lightening of one drive wheel than an independant rear, at least one of the several reasons why independant rear suspension is superior to a live axle.
On the other hand, a front driver reacts torque equally in a lateral orientation, while reacting it differently longitudinally, so each front wheel remains equally loaded. The longitudinal torque reaction will attempt to rotate the chassis backward (like a bike doing a wheelie), lightening the front wheels and loading up the rear wheels, which is unfortunate but there is nothing we can do about it, physics is physics! This problem is greater the more front traction we have, the more torque to the front wheels, and the shorter the wheelbase.
Note that this effect is not the same as weight transfer from front to rear caused by acceleration (mass, inertia, 'pitch centre' height relative to CG height), it is divorced from this source of weight transfer, being purely to do with the reaction of torque forces. If we hypothetically could lower the CG to ground level (I wish!), we would have zero weight transfer from acceleration, but we would still have some weight transfer from the torque reaction.
With front drive, any difference in side to side loading (and thus any tendency to spin one wheel before the other) will reflect static weight distribution and any irregularities in ground level, but the tendency to spin one wheel will be way less than with a live rear axle on a rear drive car, and somewhat less than with a rear driver with independant rear suspension.
The more equal the front / rear static camber, and the more similar the camber curves of the front and rear suspensions (camber curve being the camber changes with bump and rebound), the more similar the front and rear tyre wear will be (in nature if not degree), so tyre rotation will have little affect on overall tyre wear. On a Honda (or similar) with double wishbones front and rear, and if the static camber is close to the same front / rear (as your's is) the more similar the tyre wear will be.Quote:
Originally Posted by Kiz_EG6
On the other hand, if you have say Mac stuts up front (which have a very poor camber curve, gaining a lot of pos camber with roll) with substantial static neg camber, and say a live rear axle or a 'dead' beam axle (which both have camber curves at zero camber gain, meaning no camber is gained with body roll) with zero static camber, then the tyre wear will be very different front to rear, and tyre rotation may have quite a substantial affect on overall tyre wear.
There's not much we can do to equalise front / rear tyre wear short of rotation (at the possible expense of increased overall wear). It is of course a function of weight distribution, and the fact that we are using the fronts to propel the car as well as steer it (a lot of work to do!). About the only thing we can do within the parameters at our disposal is to reduce understeer, because understeer wears front tyres. Unfortunately, I doubt this will make much difference, even if it makes some.
So would I. All I was saying is that the tyre companies recommendation will be for the purpose of reducing the possibilty of oversteer in extremis. If the rear tyres are quite worn then they will most probably also be somewhat hardened by oxygen, heat and sunlight, and be less grippy than the softer new rubber as a result.Quote:
Originally Posted by mrwillz
If you put the new tyres on the front you will lessen the possibility of understeering in the wet, but you will also increase the possibilty of oversteering, in the wet or the dry. An average driver will have a much better chance of dealing with understeer than with oversteer. Lifting off is the instinctive reaction to the handling going pear shaped, and this is generally the correct thing to do with understeer, but generally the wrong thing with oversteer. Locking up the front brakes is of course a different story, the average driver will just push harder, probably removing themselves from the gene pool. The tyre company's recommendation can't cover every eventuality.
Another thing occurs to me; asuming the driver doesn't cope with understeer there is a 50/50 chance of going either into the ditch or into oncoming traffic (I know where I'd rather go if I had to make the choice!). If the driver doesn't cope with oversteer then he / she may go into the ditch, or into oncoming traffic, but there's probably more than a 50/50 chance that at least some part of the car will cross over the centre line, either directly onto the wrong side of the road (far side) or on the way to the ditch on the near side. The average driver, on average, is probably better off with understeer than oversteer, so probably better off with the newer tyres on the rear (IMNSHO).
i think JohnL put it summed it up well by saying it's aimed at the average driver who is better capable of controlling understeer than oversteer.
i'm sure Michelin knows what they're talking about and most of their customer base is the average Joe rather than buyers from this forum and others alike. Hence that advise is aimed at the average driver to have the new tyres on the rears.
It's not so much the average driver's 'capability' to better control understeer better than oversteer. I don't think 'skill' comes into it all with an average driver. It's just that the untrained reaction is to lift off if the driver gets a fright, which will get them into less trouble (or less worse trouble, if you'll excuse the appalling sentence structure!) if the car is understeering rather than oversteering. On the other hand they may completely panic and slam on the brakes which is less than good on a slippery road...oh well!
it is if you have rays nuts, and don't wanna scratch them!!! Lol..Quote:
Originally Posted by Kiz_EG6
such a pain to take of my wheels these days.
Quote:
Originally Posted by JohnL
Dude do you just cut and paste this shit off some gay ass technical site?!?
You know no one is impressed that you can take two pages to write what only needed two sentences, i can't even be bothered reaqding it!!!