Tires!

[Perd Hapley]

I finally found the time to replace the front tires on wifey's car, which were quite worn out. The rear tires are still OK. Since it is front wheel drive, it seemed obvious that the newest tires should be up front. They are the drive wheels, they have the most weight on them, and they steer, right?

The gentleman at Firestone advised us that their policy is to always have the newest tires on the rear of any vehicle they service. As he explained it, the back is the end that tends to drift (due to weight distribution), so the rear tires need more tread.

This seemed to make sense, so we told them to go ahead and do it their way.


What is the judgment of the all-wise council?

[Northwoods]

IME the front tires wear fastest.  More so on FWD vs RWD, but still applies to both.  If you have jack stands I'd go ahead and rotate those tires to get the fresh tread up front. Unless the old tires are lokely to need replacement within the next 5k miles or so.

[AZRedhawk44]

Go in for your free rotation service in the next 3K miles and get it done your way until you're ready to put new ones on the back.

[drewtam]

I've seen this new school of thought at several tire stores and work shops. The rear tire replacement is new fad BS.

The front tires carry ~70% of the braking force of the car. This is the most important aspect.
During heavy braking, additional force is transferred to the front tires, and the rear tires are unloaded. Therefore, good brakes are biased to produce the most force in the front where the traction is available.

The force expected of the front tires is compounded when you are trying to brake and steer at the same time. Most modern passenger cars have suspension designed so that they understeer at all possible conditions. Which means, they are designed so that the front tires are always the limiting factor in the traction circle. http://en.wikipedia.org/wiki/Circle_of_forces

Under acceleration additional force is transferred to the rear tires, and the front tires are unloaded. The car is front wheel drive only? Then you need extra traction up front to offset the load transfer to rear.

I always recommend having good tires on a car. DO NOT buy the cheapest plastic you can wrap around the wheel. Tires are the most important safety and performance aspect of a car.
Therefore, I always recommend changing all 4 tires when it is time to replace.

[Hawkmoon]

I finally found the time to replace the front tires on wifey's car, which were quite worn out. The rear tires are still OK. Since it is front wheel drive, it seemed obvious that the newest tires should be up front. They are the drive wheels, they have the most weight on them, and they steer, right?

The gentleman at Firestone advised us that their policy is to always have the newest tires on the rear of any vehicle they service. As he explained it, the back is the end that tends to drift (due to weight distribution), so the rear tires need more tread.

This seemed to make sense, so we told them to go ahead and do it their way.


What is the judgment of the all-wise council?

The best tires belong on the front, even with rear wheel drive. In addition to doing the steering, for most passenger cars the weight distribution is about 60:40 on the front, and under hard braking even more weight shifts to the front. You want the best tires where most of the work is being done.

Mr. Firestone man is an idiot. I'd like to see that "policy" in writing.

[zxcvbob]

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

I've seen a video demonstration by Michelin and it's pretty convincing.  Your best tire go in the back whether the vehicle is FWD or RWD because if the front tires lose traction the vehicle understeers but it is easy to recover.  If the rear tires lose traction, you lose control and can spin out.  It's not the answer I was expecting.

Edit:  I think I found the video:  http://www.youtube.com/watch?v=BaXXrKFJctU

[Perd Hapley]

Here's that URL above as an actual link:
http://www.youtube.com/watch?v=BaXXrKFJctU

And here's another.
http://www.youtube.com/watch?v=BaXXrKFJctU

Here are more links.
http://www.google.com/search?q=new+tires+rear&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[French G.]

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

I've seen a video demonstration by Michelin and it's pretty convincing.  Your best tire go in the back whether the vehicle is FWD or RWD because if the front tires lose traction the vehicle understeers but it is easy to recover.  If the rear tires lose traction, you lose control and can spin out.  It's not the answer I was expecting.

Edit:  I think I found the video:  http://www.youtube.com/watch?v=BaXXrKFJctU

Horse crap I say. All the braking load, most of the vehicle weight. Understeer is not easy to recover from when you slide right into a damn tree. In fact my default response to an understeering RWD is to gas it to break the rear loose so I can point the vehicle where I think it should go.

-Rear wheels hydoplane due to insufficient tread depth, big deal. Front wheels do same, possible calamity.

-Catastrophic failure risks go up too, front wheels carry more weight, side force from turning, etc. The carcass wears out, a vicious cycle since then the weight of the car wear them faster. Highway speed blowout is just another day on the rear of a passenger car, steering tire, could get ugly, especially if you figure out how to incorrectly react and get the side of the rim to bite pavement.

I always change 2 tires at a time, fronts go to the rear, new go on the fronts.

[dogmush]

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

I've seen a video demonstration by Michelin and it's pretty convincing.  Your best tire go in the back whether the vehicle is FWD or RWD because if the front tires lose traction the vehicle understeers but it is easy to recover.  If the rear tires lose traction, you lose control and can spin out.  It's not the answer I was expecting.

Edit:  I think I found the video:  http://www.youtube.com/watch?v=BaXXrKFJctU

Horse-pucky. Getting a FWD passenger car to oversteer without using the handbrake requires work. Best tires should go in the front, as they are handling the brunt of the traction both accelerating and  braking.

That said, I hate to hear about people skimping on tires.  If they're worn, replace them.  Tires are literally the only thing holding you and several thousand pounds of steel on the road. 

[Harold Tuttle]

Ok, I have a FT 4wd jeep grand cherokee

I had 2 worn fronts and figured I would replace both
but the tire shop says i need to change all 4 on a 4WD quadra trac II

[seeker_two]

I can kinda see the logic for having the newest tires on the rear on a RWD vehicle...your thrust-producing wheels needing the most traction, and the weight difference b/t front & rear necessitating more traction in the rear. But I'm not buying that theory for FWD vehicles....newest tires should be on the wheels that do the most work.

This is also the reason I buy tires from independent shops instead of franchises. Independents will put your tires on in any configuration you're willing to pay for without having to answer to any corporate policy. And the price difference is more than made up for in the quality of service you get from the independent shop. Besides, I'm a home-town business supporter.

[Hawkmoon]

Ok, I have a FT 4wd jeep grand cherokee

I had 2 worn fronts and figured I would replace both
but the tire shop says i need to change all 4 on a 4WD quadra trac II

Of course they say that -- that way they sell four tires instead of two.

I currently own (lemme see) eleven Jeeps -- Cherokees and Comanches (the PU version of the Cherokee). I have owned a Grand Cherokee with QuadraDrive. There is no reason why you need to replace all four tires if two are still decent. QuadraTrac II has a differential in the transfer case. The front drive shaft is not locked to the rear drive shaft, and minor differences in rolling diameter between the front and rear tires are inconsequential. There's more difference between the front and rear when you go around curves -- which is why the transfer case has a differential.

As to the video -- if your car understeers, you're toast. You cannot recover. I ALWAYS set up my track cars, my rally cars, and my street cars to oversteer slightly. I CAN recover from oversteer, in multiple ways, unless it's really drastic. And if it is really drastic and I can't recover, I would much prefer to hit the tree backwards than head-on.

[zahc]

I've seen this new school of thought at several tire stores and work shops. The rear tire replacement is new fad BS.

I agree completely.

[BridgeRunner]

This is also the reason I buy tires from independent shops instead of franchises. Independents will put your tires on in any configuration you're willing to pay for without having to answer to any corporate policy. And the price difference is more than made up for in the quality of service you get from the independent shop. Besides, I'm a home-town business supporter.

+1

I finally found the best local tire shop last year.  My tax refund/payment for being poor with kids will be here next Friday.  Next Monday, I'll be at the local tire shop getting four new tires. 

[Tallpine]

If the rear tires lose traction, you lose control and can spin out are going too damn fast.

[geronimotwo]

The best tires belong on the front, even with rear wheel drive. In addition to doing the steering, for most passenger cars the weight distribution is about 60:40 on the front, and under hard braking even more weight shifts to the front. You want the best tires where most of the work is being done.

Mr. Firestone man is an idiot. I'd like to see that "policy" in writing.

what he said

[grampster]

If one rotates one's tires at proper intervals, they should wear so that all 4 should be replaced at the same time.

[Tallpine]

If one rotates one's tires at proper intervals, they should wear so that all 4 should be replaced at the same time.

That works fine until you run a rock through one 

[grampster]

That works fine until you run a rock through one 

Don't buy a 2 pants suit.....You'll burn a hole in the coat.

[dogmush]

If the rear tires lose traction, you lose control and can spin out are going too damn fast.driving at the limit of adhesion and doing things just right.

FTFY

Ok, I have a FT 4wd jeep grand cherokee

I had 2 worn fronts and figured I would replace both
but the tire shop says i need to change all 4 on a 4WD quadra trac II

Like Hawkmoon said, unless someone slipped a locker into your transfer case while you weren't looking just change the worn out tires.  Although that is a sign you might want to rotate more frequently.