Tire configuration on 2WD front wheel drive


#1

I’ve been getting my tires done at Costco for 10+ years, and they always put higher tread tires on the rear and lower tread tire on the front. If front tires have lower tread than the rear, then they would only rotate tires from left to right and vie versa. They would not move lower tread tires to the rear.

Today, a mechanic told me since my car is front wheel drive, higher tread tires need to go to the front. Can anyone clarify?


#2

New tires always need to be on the rear of vehicle no matter what the drive method is ( front-rear-all ). Ignore that mechanic he is living in the past. A simple you tube search will fully explain why.


#3

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=52

Tester


#4

If you rotate your tires on a consistent basis (every 5k-7.5k miles), the amount of wear will be virtually the same on both front and rear tires.


#5

@jbrown70:
As you’re learning, opinions differ on this.
It’s not a matter of right or wrong. It really depends on what your main goal is.

  1. If your goal is to maximize your traction on a FWD vehicle, then put your new tires on the front.

  2. If your goal is to maximize your vehicle’s rear end stability during emergency handling maneuvers, then put your new tires on the rear.

Tire dealers and insurance companies tend to place more emphasis on the second bullet. I suspect more mechanics do as well.


#6

I disagree, it is a matter of right or wrong. In Texas a tire retailer lost a large lawsuit over this very thing. I was skeptical when I first heard the new on rear from the tire dealer but not anymore.


#7

…but if you NEVER put the “better” tires up front, you’ll NEVER even out tire wear. Since the front axle of a FWD car wears at roughly 2X the rear, the only way to “even out” tire wear is to put the tires with (slightly) more tread up front, until they even out. This is commonly known as “tire rotation.”

…and if you don’t rotate, you’ll ultimately end up with tires of vastly different tread on each axle, which is a safety issue in its own right.

The geniuses that gave us this “new and improved” rotation pattern have made some pretty pathetic assumptions of our driving skill: specifically, that we’re utterly incapable of “catching” oversteer as it happens; that “countersteering” is contra-intuitive and we’d NEVER figure out how to do it; and that going off the road, head-first, from lack of traction is preferable to having an attempt to correct oversteer, failing, and going off the road sideways.

I’d argue that their assumptions are overly pessimistic and thus flawed.


#8

The mechanic is wrong. Tire testing has shown that cars with lesser tread on the rear wheels are more likely to spin out in poor traction conditions than cars with the better tread on the rear.

A typical FWD car has about 60% of its weight on the front wheels and 40% of its weight on the rear. Greater weight means greater traction. Since the front wheels have 50% more weight on them than the rears, they have a traction advantage. To keep the traction between the front and the rear balanced, it’s better to have the tires with the better traction on the end with the lesser weight… the rear.

Most shops now do this as policy for the reason highlighted by Volvo… liability. In a society as odiously litigious as ours, where some people are always looking for every opportunity to sue somebody (winning has been called “the tort system lottery”) no shop wants to leave itself vulnerable.

In summary, the tires with the best traction go on the rear to compensate for the traction advantage inherent in the front’s greater weight.


#9

The lawsuit I read said the tire dealer lost because it was against the company’s policy. Even more ironic was even the older rear tires had adequate tread.

As an individual, you can install the newer tread on whatever axle you prefer. I usually install mine in the rear, but those who choose the front are simply making a tradeoff that traction is more important to them. Are they wrong, or are their priorities different than others?


#10

No it doesn’t.

Tires become “less sticky” the more weight they carry, per square inch of surface area. This is why “performance” vehicles have giant “steamroller” tires to maximize grip, versus “pizza cutter” tires. Putting more weight on the front axle means that axle will give up grip first, absent handling tricks like sway bars to correct this tendency.

On a skidpad, a FWD car will tend to give up grip on the front axle first, causing understeer. Putting the tires with the best tread in the rear will make it more likely yet to understeer (in rainy/snowy conditions). Given that FWD cars are already so understeer-prone, IMO you can afford to give up a little bit of understeer bias, where you probably wouldn’t want to in a rear engine/RWD car like the Porsche 911.


#11

Yes, it does.
If more weight equaled less traction, tractor trailer trucks would have a terrible time getting up inclines.

Try tying a rope to a plate and pulling it across the kitchen floor.
Now have an adult stand on the plate and try pulling it across the floor.
Under which loading situation was the traction of the plate the greatest?

On a skidpad, a FWD car will give up its traction on the front first because under heavy acceleration that’s the end that’s getting torque loaded by the engine. A RWD will give up the rear wheels first because THAT is the end getting torque loaded by the engine!

Performance vehicles have wide tires because they exceed the load-per-square-inch at which traction is no longer able to be maintained. But the goal of performance vehicle is to be able to increase the loads, so they use wider tires. That reduces the load per square inch hopefully below that at which the tires break traction. That does NOT mean that the total load on the tires has been reduced, NOR that the total traction has been reduced. only the load per square inch. Total load capacity is the goal, and that’s a function of square inches X applied load.

Dragsters use “ripplewalls” to allow the tires to distort and apply as many square inches to the pavement as possible. That distributes the load, and a dragsters driver’s goal on launch is to keep the torque just at the point where the tire still has traction. It’s called “hooking up” to the pavement.

You’re confusing traction per square inch with total traction.


#12

You know what I get a kick out of?

Is when somebody comes on this board and asks a simple question, and people will refer them to web sites that are authorities on the subject.

But somebody else on this board comes up with their own opinion on the subject, but is unable to cite one single web page that supports their claims!

I laugh!

Tester


#13

So you think that no opinion is valid unless a web page can be cited to support it?
That makes me laugh.

Do you think that nobody on this forum has sufficient knowledge to have an “authoritative” opinion?
How about retired engineers and professors? Certified mechanics? Are they “authoritative” only when doing engineering, teaching, or wrenching?
What qualifies you to judge their opinions?

Is it possible that people should have a right to their opinion without being criticized even if their opinion is wrong?

What was the point of your comment?
Do you have anything constructive to add to the question at hand?


#14

Do you mean this is the advice you get from Costco when you buy two new tires, and want to keep two others in service? That they put the new ones on the back, and the old ones on the front? I guess I could argue it either way, but I’d be inclined to go along with what they say. They work with tires all day long and are the tire experts. Good idea to rely on what they say. No harm asking here tho.

Me, I wouldn’t complain if they offered that advice to me b/c while I might prefer the better steering and braking with the new ones on the front, I’d be thinking more important than that, I’d rather not have the back end sliding around during turns and skidding when braking, with the less weight in the rear. I do the same on my Mt Bike, the best tire goes on the rear, for the same reason.

I’m a little surprised when rotating they swap left to right tho. My understanding is that this isn’t usually recommended. That it is best to keep the tires rotating in the same direction they were first installed.


#15

A non-professional driver can usually recover in time when a car understeers due to the front tires losing traction. A non-professional driver is unlikely to recover at all when a car oversteers and goes into a spin due to the rear tires losing traction.


#16

Assuming that was directed at me, Tester, I have no need for a “works cited” page, because the primary claim I made–that “better tread on rear” is designed to favor understeer versus oversteer–is openly touted by the proponents of the tactic as why they do it. Understeer is self correcting; oversteer requires a modicum of skill to correct.

And again, we’ve known this for a looong time; well before the “push” was made to change the SOP. Presumably, the Powers That Be decided we were even worse at “correcting for oversteer” than they had previously assumed, and changes were in order.

The only other claim I made was that “better tires to front,” strictly interpreted, forbids rotation. This is quickly proven via logic: drive with identical tires for 10,000 miles, then rotate. At the time of rotation, however, the fronts (on an FWD) have worn more than the rears, and rotating them would put (slightly) worse tires on the rear axle. Which is forbidden, if you take the recommendation literally.

What additional citation is needed, Tester? I’m accustomed to using the AP Guide to Style as my guide for annotation…will that work? Do you need a works cited page, or is parenthetical citation sufficient?


#17

Gee, I didn’t know I was a “professional driver!” :wink: Really, oversteer is no big deal…anyone who has driven RWD in the snow is intimately acquainted with it, and how to correct for it. (It’s a big deal if you’re an incompetent driver, I suppose.)


#18

[quote=“meanjoe75fan, post:7, topic:106014”] … The geniuses that gave us this “new and improved” rotation pattern have made some pretty pathetic assumptions of our driving skill: specifically, that we’re utterly incapable of “catching” oversteer as it happens; that “countersteering” is contra-intuitive and we’d NEVER figure out how to do it; and that going off the road, head-first, from lack of traction is preferable to having an attempt to correct oversteer, failing, and going off the road sideways.
[/quote]

Sorry, but that is not correct.

I used to work for a major tire manufacturer who used to demonstrate why new tires should go on the rear - AND - it was impossible to prevent the car from spinning out (given the set up)

Plus, the issue is with the good tires on the rear, you were pointed ahead when your control came back. Otherwise, you were facing the wrong direction and had to go further before you could get faced the right way and could steer around objects.

We sent hundreds of folks through this and no one could prevent the car from spinning out.


#19

That’s an interesting observation… and, while I can’t support it with data, is one I agree with.
Having spent my entire life in regions with winter weather I can tell you that I’ve seen numerous spinouts… and the drivers never seem to react properly. They panic and either correct in the wrong direction or overcorrect.

I learned in a go-cart when very young and a parking lot when I got my license. But perhaps a natural inclination toward stuff mechanical was an advantage.


#20

I keep it simple by having the professionals rotate and inspect the tires every 5,000 miles and don’t worry about it.