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Post by silverdragon on Apr 26, 2013 8:14:01 GMT
This is a new one on me, but apparently, its held as "Valid" for a certain amount of valid....
As in, I was "Told" by someone who hold certain credence as a "Knows what he is doing" mechanic.....
Front wheel drive chews tyres.
Front wheel versus Rear wheel drive..........
This topic come up many times before under various discussions of who is best, but lets not go there, this is all down to TOTAL tyre wear.
It has been suggested that Front wheel drive vehicles wear out the whole set of tyres faster than rear wheel drive, in total mileage.
This is presuming that every 5,000 miles or so you actually DO "Rotate" the tyres, as in swap the front tyres for the back, to even out wear....
But it is seriously believed that front-wheel drive vehicles will wear through a complete set of 4 tyres quicker than a rear wheel drive....
And I cant work out why.
Reasons given the front wheels do all the acceleration, steering, braking, cornering force, and a whole lot of other stuff thats "Technical" (Beyond me... I am a driver not a fully fledged mechanic)
So they wear out faster...
Hang on a moment.
Read Wheel Cars... the only thing different is the rear wheels do the acceleration?..........
But SOMETHING does the acceleration, doesnt it?....
So there is a tyre getting worn by that acceleration?...
Suggested Test...
Well, My idea... if anyone has a better one, please join in?...
Two complete sets of tyres of identical make will be needed...
Measured to give exact tread depth etc.
Take a landy... Land Rover...
Or any other similar?...
One of them with the forest of gear sticks that allows choices of different drive patterns, including the choice of front wheel drive and rear wheel drive ONLY.
Lock it in Rear wheel drive and do a couple of thousand miles worth of road work.
Change tyres.
Lock it in FRONT wheel drive and repeat......
I would also suggest doing a test in 4 wheel drive just for comparison sake, as I have been told that permanent 4wd "Chews tyres" as well?...
I think that is down to how you drive...?
If you NEED a 4wd for certain jobs, like working in rough country on difficult roads, I suspect that chewing tyres is "Par for the course"?....
My Thinking.
Going onwards, changing tyres, and how often you do that.
In a smaller euro-box shaped vehicle, think the new Mini or even the Prius for instance, the tyres are naturally smaller, lighter, etc?...
The car its self would more likely be found as a 4-wheel shopping trolley, a resident of Urban suburban commuting short journeys with lots of corners junctions and the rest, so LOTS of stop starting....
This in its self, per mile, MUST be heavy on tyres?...
A Larger 5seat-plus-luggage highway cruiser that has BIGGER tyres, and its natural habitat is Motorway/Freeway long journeys, perhaps less tyre wear?....
Plus wheel size.
You can get more tyre, therefore less wear per mile, on a 20 inch wheel than you could on the old Mini that had 10 inch wheels.....
Therefore, as most small urban commute vehicles are front wheel drive, its sort of no surprise they turn up for new tyres more often?...
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Post by the light works on Apr 26, 2013 11:47:13 GMT
the only valid argument of FWD chewing up tires is that, as my dad taught me at a young age: overhard acceleration wears the drive tires faster.
overhard cornering wears the steering tires faster.
after which I made a point to corner harder, as I had been wearing the back (drive) tires faster than the front.
but with a front drive car - both actions wear the front tires faster.
my truck wears the front tires faster, because I am balancing an 11,000 pound truck with two tires at the front and 4 at the rear. similarly a front drive car seems to have around 75% of the weight on the front tires, while a RWD car seems to typically have a 50/50 weight ratio.
as far as four wheel drive - I think that would be partly because of the weight, but with a car left in 4 wheel drive, the front and rear axles seem to never actually be driving at the same speed, so one is nearly always pushing or pulling the other. (all wheel drive adds a differential in the middle to reduce that)
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Post by watcher56 on Apr 26, 2013 16:05:32 GMT
Technically, you probably should not rotate tires on a front wheel drive vehicle.
1. Tire manufacturers and 'experts' have been adamant that the better tires should be on the rear.
2. If a front wheel drive car wears front tires faster than rear (and I believe it does), then even after only a few miles, tires that started out the same (new tires) would be more worn in the front than in the rear. Rotating these tires would violate #1.
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Post by srmarti on Apr 26, 2013 21:04:48 GMT
I'll just give my opinion and leave it at that. Feel free to agree or disagree.
In a front wheel drive car, the front tires are doing most of the work, thus wear somewhat faster.
- Often the weight distribution is greater on the front as the drive train is at that end.
- The front tires are handling most of the acceleration load. They accelerate the car and maintain it's velocity. During braking weight transfer is forward and the front does more of the work than the rear tires and brakes.
- The front tires are doing the steering.
-With front wheel drive, the environment the rear tires experience is more or less like those on a trailer tagging along for the ride.
Without rotation front to back to equalize wear, the front wear much faster. Same overall as a rear wheel drive car if tires are rotated on both? Don't know, seems like too many other factors could have more influence to come up with a all encompassing conclusion.
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Post by silverdragon on Apr 27, 2013 8:44:46 GMT
Its a given that FWD will wear front tyres faster than back.
But I will disagree strongly with those "Experts" mentioned in Watchers post, who I believe are the same "Experts" who tell you you probably should change al four tyres at the same time... they are just trying to sell tyres.
In a FWD drive, you need the better tyres up front, to give you better grip.
If you can stop faster, chances are your ABS will sort out the tail for you and stop it overtaking the front any way, so, in these days of the alphabeti spaghetti of all those electronic driver aids that prevent you over-driving a car by independently grabbing/releasing just the one brake as part of traction control, in a FWD, why DO you need the better tyres at the back?...
And if you have a better set of tyres at either end by any significant amount, shouldn't you have already rotated 'em by now?....
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Post by the light works on Apr 27, 2013 14:15:35 GMT
the "better tires in back" rule only applies if there is SIGNIFICANT wear. otherwise, the better tires should be rotated to the end that wears them faster.
and on a FWD, that IS the front, for the reason I mentioned above.
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Post by c64 on Apr 28, 2013 8:44:56 GMT
The most wear is caused when braking, a common car brakes 80% on the front wheels because they have more weight on them and can handle more braking forces. Also if the rear wheels lock first, the car turns unstable and can spin around very easily. When the front wheels lock, the car just glides straight.
To make sure, the rear wheels lock last, the braking balance of cars is set to 80% front. The only exception are cars with a brake balance regulator or advanced ABS (as built into ESP).
With a variable brake balance, the car starts to brake 50:50 and when the rear of the car lifts up, the brake pressure of the rear wheels is reduced. Older cars use a brake balance regulator which was invented by NSU, it's basically a second brake cylinder connected to the rear axis stealing brake pressure when the springs of the rear axis extend. The modern equivalent is the ESP doing basically the same using its g-force sensors. On very slippery roads, the old mechanical system is a lot better since it automatically adapts to the load balance of your car, the ESP can't know how much stuff you have in your trunk and has to wait until the wheels are about to lock to know how much to compensate. During braking hard in turns, the ESP is better since it can control the wheels independently.
A car with a variable brake balance saves a lot of wear on the front wheels. The tire wear is exponential to the braking forces on the wheels so balancing the brake forces will reduce the overall wear dramatically!
If the car has a fixed brake balance, a RWD car has less wear on the front wheels since while braking, the engine helps braking on the rear wheels. There is no need to make the brake on the front wheels brake extra hard to compensate the engine braking since the differential makes sure that when one rear wheel locks, the engine even adds power to the wheel which is still spinning easing the braking force on it so it can keep the car stable very easily. This is one of the reasons a RWD car will save overall tire wear and is still save to use even in a tight situation!
Another difference between RWD and FWD is the wheel tracking. The front wheels are never set parallel!
A FWD car has a "positive toe". The front wheels are pointing to the sides of the lane in a "V". When the engine adds power to the front wheels, the forces set them parallel. So with your foot on the accelerator, there is no extra wear on the front wheels but when coasting, you get extra wear which becomes a lot worse while braking!
In case of a RWD car, you have a "negative toe", the front wheels point to the center of the lane in a distance and form an upside down "V". When you have your foot on the accelerator, the forces pushing the front wheels set them in parallel, too. But this also works somewhat when coasting and when braking the "positive toe" caused by the braking forces is a lot lower so you don't have that much extra wear on your front wheels when you release the accelerator.
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Post by the light works on Apr 28, 2013 13:50:18 GMT
if your throttle is shifting your toe-in you need new steering hardware.
here, all cars have a very slight toe-in, as that tends to cause the car to want to return to a straight line down the road. old truckers would set the least toe-in they could, as that made it less effort to turn around corners.
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Post by srmarti on Apr 29, 2013 18:09:40 GMT
if your throttle is shifting your toe-in you need new steering hardware. here, all cars have a very slight toe-in, as that tends to cause the car to want to return to a straight line down the road. old truckers would set the least toe-in they could, as that made it less effort to turn around corners. On front wheel drive it seems unlikely that the components would be rigid enough to completely prevent toe setting changes. |
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Post by GTCGreg on Apr 29, 2013 20:05:07 GMT
The front tires wear out faster on nearly all cars, FWD, RWD and 4WD. On Front drive, they tend to even wear out a little faster. The main difference in wear between the front and rear tires is caused because the front tires are the ones used to steer the vehicle. Add a little misalignment in the steering system and it even makes it worse. And as others have already pointed out, sometime there is deliberate toe in, which may be desirable even though it adds to tire wear.
Every car I've ever owned wore the front tires faster than the rear. None were front drive only vehicles. That's why you rotate the tires.
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Post by the light works on Apr 29, 2013 22:15:49 GMT
The front tires wear out faster on nearly all cars, FWD, RWD and 4WD. On Front drive, they tend to even wear out a little faster. The main difference in wear between the front and rear tires is caused because the front tires are the ones used to steer the vehicle. Add a little misalignment in the steering system and it even makes it worse. And as others have already pointed out, sometime there is deliberate toe in, which may be desirable even though it adds to tire wear. Every car I've ever owned wore the front tires faster than the rear. None were front drive only vehicles. That's why you rotate the tires. obviously, you were not accelerating aggressively enough. |
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Post by GTCGreg on Apr 29, 2013 22:32:22 GMT
obviously, you were not accelerating aggressively enough. It wasn't me. Nothing I've ever owned COULD accelerate aggressively enough.  |
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Post by silverdragon on Apr 30, 2013 8:09:54 GMT
I had a car like that... its nought-to-sixty times came with a calendar?...
However, it was a diseasel... (diesel) 2ltr engine, could tow a house all day long, could manage a two ton boat-and-trailer hundreds of miles without hardly needing to slow down, would do a 55mph (sensible) long distance over mountains towing that boat without missing a beat.
It WAS power assisted steering...
For a car built in the 80's, that was pretty "New", it was the first power steering I ever owned in a car, but as the engine alone weighed in at nearly a ton, that over the front wheels, you needed that....
I would have kept that car for many a year, but I stopped at a set of lights (That were on red) and the "person" behind me didnt......
Ok, we have consensus that the front tyres WILL, without a shadow of a doubt, wear out faster than the rear....
How are we doing with the question if Front wheel drive cars when considered against TOTAL tyre wear, will go through tyres faster than an equivalent Rear wheel drive car?.....
Presuming identical tyres on similar vehicles, taking occasional tyre rotation as good maintenance and normal.
I am also presuming identical driving habits....
I know someone who's driving habits are a little questionable, to that, he tends to change tyres as often as tax discs?... once a year, he comes out with the line "I should get some new tyres before winter"....
I know his car, his annual mileage is about 18- 20 thousand.....
His vehicle is used for work, granted, but I would expect a little more than 20 thousand from a good set of tyres?....it is a commercial type vehicle after all (small van) and should get better mileage....(Given that his tyre size is similar to mine, and he chooses deep tread all weather tyres of harder* compound..)
(*When compared to extremes such as "Black-snot" type racing tyres?...)
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Post by c64 on Apr 30, 2013 9:57:25 GMT
if your throttle is shifting your toe-in you need new steering hardware. Not if your car is different from this one:  What do you think the rubber part of the wheel and all the little rubber buffers in the steering hardware do? here, all cars have a very slight toe-in, as that tends to cause the car to want to return to a straight line down the road. old truckers would set the least toe-in they could, as that made it less effort to turn around corners. The slight toe-in is for RWD, the effort to turn around corners and how strong the car will try to drive straight is controlled by the offset steering. While a negative one is a lot harder to install in a full engine bay, it makes turning around corners a lot easier. Very old cars have a positive offset steering which won't take up much space around the front wheels but it makes steering very hard so very old cars either really need a power steering or they have a very odd steering gear transmission ratio. My Passat 35i is famous for a very intense negative offset and a very short steering gear transmission ratio. With the very unique position of the gearbox and drive shaft angle, the car can take very tight left corners with just 3 revolutions of the steering wheel, you can make an U-turn in a pretty narrow road and you wouldn't miss a power steering since as long as it is rolling forwards, the steering wheel is very easily to turn. Unless you move it in reverse, then the steering wheel tends to try to break your arms if you don't have a power steering. The steering system of this car is very complex and needs proper adjustments, there is not much room for any wear. But when it's correctly adjusted (and not worn), the car fully ignores cross-winds, it will always counter steers automatically. If the steering hardware is worn, uneven roads can make the car try to go left or right out of a sudden but there is a simple modern solution to prevent just that. Replace all the rubber parts with polyurethane ones. |
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Post by c64 on Apr 30, 2013 10:05:15 GMT
Every car I've ever owned wore the front tires faster than the rear. None were front drive only vehicles. That's why you rotate the tires. Try the Passat B2  With its very long wheelbase and little weight on the rear wheels along with its crude rear wheel suspension, the rear springs tend to oscillate. While mathematicians think that squaring the circle is impossible, this car just does it. Gently pull the E-brake at ~50mph and it can bounce like a lowrider! My first car was one of those. Owning this car, you are not concerned about spreading the wear, you are concerned that the car will destroy the rear wheels if you don't rotate the wheels! |
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Post by the light works on Apr 30, 2013 12:36:53 GMT
keep in mind one of the pieces of equipment I drive on occasion is a 1942 Ford fire engine. I will tell you also, that in the 70s my dad's brother was head mechanic for his father's trucking business. I have been taught about the effect of toe-in. (most of the drivers wanted zero toe-in, so the steering wouldn't fight them going around corners.)
I say, again, if there is enough flex in your steering to affect your alignment, there is a problem with your steering.
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Post by the light works on Apr 30, 2013 12:40:33 GMT
and for the last 5 years, I have ground through a set of tires every year on my work truck - because of the extra weight, and not helped by the fact that the guys at my old tire center did not inflate them properly. my current set of tires cost me three times as much, and I hope they will last at least 3½ years.
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Post by c64 on Apr 30, 2013 16:06:29 GMT
I say, again, if there is enough flex in your steering to affect your alignment, there is a problem with your steering. There is no way to have zero tolerances. Maybe on a truck where the axis doesn't move much you can make the steering hardware "solid", but you can't do that on a car. And how do you plan to prevent that the tires can flex except filling them with concrete? |
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Post by GTCGreg on Apr 30, 2013 17:30:46 GMT
And how do you plan to prevent that the tires can flex except filling them with concrete? But then they won't go flat. |
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Post by silverdragon on May 1, 2013 6:25:40 GMT
And how do you plan to prevent that the tires can flex except filling them with concrete?
The racing way would be low profile.
Larger wheels and less tyre wall, not as much flex.....
But then the ride become so uncomfortable, if you run over a coin you can tell heads or tails.
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