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View Full Version : Rear Wheel Drive Vehicle, 2 New Tires, Front or Back?


jaw04005
May 5, 2008, 12:03 AM
I'm getting two new tires for my Mustang. The two back tires are the ones that need to be replaced.

My dad and grandpa are insisting that I have the tire shop put the two new tires on the front, and move my two good tires from the front to back.

However, the tire shop disagrees since my car is rear wheel drive. The shop says I need to put the two new tires on the back. They even gave me a guide explaining why good back tires are important.

Also, several of the tire manufacturers urge you to put your new tires on the back also.

http://www.goodyeartires.com/faqs/Technical.html

My tires are still on back-order. Any thoughts?

strider42
May 5, 2008, 12:08 AM
I'd probably go with the people who make their livings studying such things and took the time and expense to print up literature about it.

Sun Baked
May 5, 2008, 12:12 AM
Putting 2 tires with the most grip on the front can cause the back end to break loose and the car to spin out in a panic stop.

Putting the good tires on the rear puts the most grip on the back, hopefully balanced with the front during panic stops.

At worst the rear grips more than the front the car is being pulled to a stop, and doesn't want to swing around.

---

aka, Putting the good tires of the front could make the panic stop a handful as the car gets squirrely.

Edit: Also forgot to say that most weight + old tires (aka front) = most grip for old tires ... sticking them on the light side of the car takes poor grip tires and makes problem worse, and compounds that in a panic stop when even more weight and grip is removed from the tires.

Counterfit
May 5, 2008, 12:39 AM
Well-worn tires generally have MORE grip in the clean 'n' dry than less worn.

What you need to consider most here is hydroplaning resistance. Deeper tread is better than shallower tread (assuming same model and size of tire). Therefore, you should put the more worn tires at the front, and put the new ones in the back. This way, is you start to hydroplane, you'll understeer, which is fixable by just letting off the gas some. Otherwise, if the rear tires start to hydroplane first, you'll start to oversteer, which, while fun in a controlled environment, is not so fun on a crowded highway.

Especially when that semi t-bones you...


Everything you wanted to know about tires, and much much more (http://www.tirerack.com/about/techcenter.jsp).

benlangdon
May 5, 2008, 01:22 AM
Well-worn tires generally have MORE grip in the clean 'n' dry than less worn.

What you need to consider most here is hydroplaning resistance. Deeper tread is better than shallower tread (assuming same model and size of tire). Therefore, you should put the more worn tires at the front, and put the new ones in the back. This way, is you start to hydroplane, you'll understeer, which is fixable by just letting off the gas some. Otherwise, if the rear tires start to hydroplane first, you'll start to oversteer, which, while fun in a controlled environment, is not so fun on a crowded highway.

Especially when that semi t-bones you...





Everything you wanted to know about tires, and much much more (http://www.tirerack.com/about/techcenter.jsp).

ya...
first
well worn tires with less tread are not sticker than new tires with a lot of tread.
you might think its a slick sports tire or something but real racing tires if there slicks, get to a point where they suck. this is the point where you have no more tread left on the tire.


sure people shave r compound tires 1/32 or two, but that in no way is making that tire a slick,


i didn't read what you posted as i am pretty sure im correct and should be doing my homework instead of this.
hey if im wrong.
at least you know that is right

scotthayes
May 5, 2008, 02:50 AM
Well-worn tires generally have MORE grip in the clean 'n' dry than less worn.


That is so wrong it's scary. As benlangdon said, a well worn tyre (sorry, using the English spelling) will not have more grip. The slick tyre used by racing teams have a much much softer rubber than a normal road tyre, thus generate more heat which adds to the grip. Any sign of uneven wear or a tread depth of 2mm or less and mine get changed.

As for the OP, I'd listen to the tyre man and manufacture when it comes to where to stick the new ones.

benlangdon
May 5, 2008, 03:07 AM
frankly
you should get all new
keep one for the spare (if you have a full size spare, which ford prob skipped)
and fing rotate your tires
jesus christ :rolleyes: (as mr slave would say)

i have 280 tread wear tires
and i go around right turns a lot more than left turns (well hard turns) everyday and i rotate mine more than normal.

yet all my tires have equal wear.

o ya i drive a rear wheel drive car also.


ya 2nd edit.
i should mention those people who shave a little do this so they do not have to wear the tire in to get it i guess you could call it tempered, but even then it should go through a heating cycle
and if they are a any team they would bake there tires before they even touched them, and wouldn't touch them at all.
im rambiling now
need sleep

ya... worn tires are good for one thing
burnouts, and coffee tables

prostuff1
May 5, 2008, 12:38 PM
I'm getting two new tires for my Mustang. The two back tires are the ones that need to be replaced.

The question we should be asking is why do you only need back tires? Of course we know the answer to this question but that is not the point. I realize it is probably fun to do burnouts but you will soon come to realize tires can get expensive quick.

My opinion is to do what one of the other guys suggested and get 4 new ones. Then use one of the remaining two good ones as a full size spare. Then, stop doing burnouts and screwing up your tires. When you get your tires get them from a place that offers lifetime balance and rotate. I usually get tires from firestone and get the lifetime balance and rotate along with front end alignment package. That way every time i take in the vehicle for an oil change i get the tires balanced and rotated and the front end aligned.

iJohnHenry
May 5, 2008, 12:55 PM
I'm with your Dad and Grandpa on this one.

In the wet, I want some tread on the front.

I am less worried about doing donuts, but then I don't drive in that fashion.

benlangdon
May 5, 2008, 01:29 PM
The question we should be asking is why do you only need back tires? Of course we know the answer to this question but that is not the point. I realize it is probably fun to do burnouts but you will soon come to realize tires can get expensive quick.

My opinion is to do what one of the other guys suggested and get 4 new ones. Then use one of the remaining two good ones as a full size spare. Then, stop doing burnouts and screwing up your tires. When you get your tires get them from a place that offers lifetime balance and rotate. I usually get tires from firestone and get the lifetime balance and rotate along with front end alignment package. That way every time i take in the vehicle for an oil change i get the tires balanced and rotated and the front end aligned.

kinda forgot about that
alignment
i get one almost every new set of tires.
on second set this year :( 1600 down the drain
maybe you have a lot of toe out or in in the back
that will wear tires down fast.

o ya get the most expensive tires you can afford.
tires are the only thing that touch the road.
what good is a 3k coilover setup with 195/60/15 and a tread of 900+
just saying.

ChrisA
May 5, 2008, 01:47 PM
My dad and grandpa are insisting that I have the tire shop put the two new tires on the front, and move my two good tires from the front to back.

However, the tire shop disagrees since my car is rear wheel drive. The shop says I need to put the two new tires on the back.

Your dad and grandpa are thinking that if a tire were to blow out you'd prefer it to be a rea tire. In this respect they are correct.

Also they are thinking about economy. In your car the front tire get "used up" faster and the rear tires will last "forever".

I think the tire company is thinking about handling and braking performance and legal liabilty. If they place them on the rear and something goes wrong it is less likey to cause an accident.

adk
May 5, 2008, 02:05 PM
I'm with your Dad and Grandpa on this one.

In the wet, I want some tread on the front.


Why? If it's wet or icy, having tires with better tread on the rear tires will keep your car pointed straight ahead in an emergency stop. Having the front tires grip better than the rears will inevitably cause the rear end to slide out, which is quite dangerous.

operator207
May 5, 2008, 04:11 PM
Stop peeling out if you have warn out your rear tires and not your fronts. How many miles do you have on these tires?

I think of it this way, your family wants you to put the used front tires on the back because the cost of tires is not cheap. You have proven your going to wear out your rear tires quicker than your front. Your family does not want you to have the new tires wear out before your older front tires do.

I agree with them.

The garage wants you to put them on the back, so you will wear them out faster, and buy more from them.

I agree they are thinking that primarily, and their secondary thinking is not wanting to do more work by moving the fronts to the rear, adding the new tires to the front, and losing money in both manual labor, and you not burning through their tires faster.


Put the new ones on the front, your car has a majority bias for braking towards the front. And you steer with the front of your car. If your rear tires lock up, ya you could possibly spin out. But if your front lock up, you have no steering, and will spin out.

Counterfit
May 5, 2008, 04:39 PM
Put the new ones on the front, your car has a majority bias for braking towards the front. And you steer with the front of your car. If your rear tires lock up, ya you could possibly spin out. But if your front lock up, you have no steering, and will spin out.

1.) Hydroplaning is the major issue at hand.
2) If your rear tires lock, you will almost certainly oversteer if you try to steer, and unless you know how to handle that situation in your car, you're boned.
3) If your front tires lock, you'll obviously take longer to stop on hard surfaces (not gravel though), and you won't turn at all if you try to steer. This is easier to fix, by letting up on the brake to give your front tires grip again.

Of course, ABS makes locking under braking moot anyway.


Now, on to worn vs. full tread tires in the dry. (bold is mine)
One of the reasons radial racing slicks are so effective is because they feature shallow tread depths and their contact patch acts as a single unit. However, any tread design breaks up the contact patch into smaller elements and additional deep tread depth (required to enhance wet traction) allows tread block squirm which will reduce dry performance. This means that tires typically provide their worst wet traction ... and their best dry performance just before they wear out. However, its also important to remember that the heat generated every time a tire is driven activates bonding agents in the rubber. As this process is repeated continually throughout the tire's life, its rubber compounds gradually harden and lose flexibility reducing the tire's grip. Therefore, a shaved "new" tire will provide more traction than a tire worn to the exact same tread depth after being driven for thousands of miles on the road.

So, nearly worn tire = bigger contact patch, which is exactly what you want in the dry. The rubber is quite as sticky anymore though, but it's better than squirmy tread.

Quick rank, for dry performance:
1. Real slick
2. shaved new tire (shallow tread + fresh rubber, possibly has lubricant on the tread if they used any when shaving)
3. nearly worn out tire (shallow tread + old rubber, no lube on tread)
4. brand-new tire (deep squirmy tread + fresh rubber, lube on tread from the molding process. Takes a few hundred miles to remove.)

Of course, any rubber >>>>>>>>>>> the casing of the tire, so there are obviously limits.

VicRattlehead
May 5, 2008, 04:56 PM
when i had my car running (350+hp rearwheel drive tbird) id go through 2 sets of tires a summer, i usually run a different size tire in the front vs the rear so i always put the new set on the rear. ive gone about 8:2 rear:front tires. put them on the rear.

what tires are you putting on the stang?

davidwarren
May 5, 2008, 04:59 PM
I assume they are all the same size tires? Why not just all four?

Counterfit
May 6, 2008, 12:57 AM
I assume they are all the same size tires? Why not just all four?

Well, if two are still over 5/32" or so of tread depth, there's no reason to replace it unless you have monsoons every week.

benlangdon
May 6, 2008, 03:25 AM
So, nearly worn tire = bigger contact patch, which is exactly what you want in the dry. The rubber is quite as sticky anymore though, but it's better than squirmy tread.

Quick rank, for dry performance:
1. Real slick
2. shaved new tire (shallow tread + fresh rubber, possibly has lubricant on the tread if they used any when shaving)
3. nearly worn out tire (shallow tread + old rubber, no lube on tread)
4. brand-new tire (deep squirmy tread + fresh rubber, lube on tread from the molding process. Takes a few hundred miles to remove.)

Of course, any rubber >>>>>>>>>>> the casing of the tire, so there are obviously limits.



are you kidding me?
did you get this from personal experience or actually something viable, and not just from what you think.

i am not saying i am right. hell someone correct me cause i would like it right.

lets say this.
a "racing slick"
is not better than a coarsely treaded tire.
it depends on the actual rubber not the tread.
formula one, somewhat of a tread.
formula 3000 or something (its very low powered car used for getting higher up in racing and learning) has a slick. and it defiantly not sticker than the treaded formula 1 tire



2nd
my last set of tires.
fresh.
where really sticky when i got them
half way through, they dropped off a cliff in terms of stickiness.


3rd
"lube"
will be worn off if you go around a couple turns somewhat hard.
this "lube" is not from the tire company, its from the tire selling company trying to make it look nice.
again, i have done this. i tried seeing how good the tire was first day i got it. it understeered and oversteered a few times, thats it. a few times, in one day.


4rth
to be honest i have no clue why people shave there tire, i know in drag racing the clean it but do not shave it.

5th
when the do shave a tire, or cut more tread into it they cut it they do not shave it, there is no lubrication.

6th
haviing less tread does not make a tire better as already stated.

7th
and this worn tire = bigger tread patch.
this might, if it does or not correct me
changing from a 225 to a 235 tire is 10millimeters, now a 225 might go into a 226 if it happens, but do you know how much a millimeter is?
ten bucks says you can not tell a difference between the same wear rating on a tire from 225 to 235, experience will tell you but if your a novice i highly doubt it you will be able to tell, and if you were a pro, you would not be saying, shaving a tire gets fresh rubber. its all the same age. graining might happen, but that is on very very expensive tires that wear out very very quickly and are definatly not street legal, and then you need to just not push on the tire so much and it will go away.


now.
i wish i could have made that really clear and informative, but i am tired, and still in the middle of finishing a research paper

i was just so taken that you might actually believe what someone will say on here
im not saying you should believe me, joe blow, or schumacher
just wanted to help, well sort of

side note. you will envitably be replaceing those worn out ones
so who gives a f$*(
where do you live anyway.
this hydroplanning c*$( can be solved one way and should be solved this way, go slow you *$(#, its raining.

173080
May 6, 2008, 09:24 AM
Putting the new tires in the back will give the car a tendency to understeer, which is safer for most drivers. That's probably why the shop wants to do it.

Putting the new tires in the front will cause oversteer, which is more difficult to control but a lot more fun. This is what I would do.

Counterfit
May 6, 2008, 02:13 PM
3rd
"lube"
will be worn off if you go around a couple turns somewhat hard.
this "lube" is not from the tire company, its from the tire selling company trying to make it look nice.
That lube IS from the tire company so that it doesn't stick to the mold while it cures.
4rth
to be honest i have no clue why people shave there tire, i know in drag racing the clean it but do not shave it.
Shallower tread = less tread squirm = better response to inputs
7th
and this worn tire = bigger tread patch.
this might, if it does or not correct me
changing from a 225 to a 235 tire is 10millimeters, now a 225 might go into a 226 if it happens, but do you know how much a millimeter is?

It's not gaining width when it wears, but when the tread depth is nearly gone, the rubber at the bottom of the tread grooves starts coming in contact with the road surface.

ErikCLDR
May 6, 2008, 03:08 PM
I would take the professional opinion. It sounds logical to me.