To rotate or not rotate

We have bought at least 14 brand new front drive cars, the first in 1978. The earliest to trade was at 35,000 miles, the latest to trade at 140,000 miles. Brands were 2 from Chrysler, 5 from VW, 1 from Ford and the remainder from GM. I have not yet encountered one front driver, with radial tires in all instances, that could do without tire rotation. If the tires were not rotated, the rear tires would develop flat spots or scallops on the outer treads. Can’t say that all of those cars had bad shocks or bad alignment.

With rear drivers, rotation may not be as critical; we have had those too with radial tires.

The rusty dodge above the article had all seasons on the front and snows on the rear. Read what Peter says about stopping. I know it sounds unlogical but you should try it.

I don’t think I read you wrong. The idea behind all treads being the same is that there will always be a traction difference if not. Snows on back may mean better traction in rear in snow, but could be significantly worse on dry pavement and in rain if block tread design or poor rain performance which is often the case with cheaper snows. Studded snows can even “skate” on dry pavement when new.

In the case of worn tires on front, generally they can have “better” traction on dry pavement, again with rear new tires having less. Enough of a difference to “cause” loss of control. Maybe not; but with respect to your general assertion avec FWD, maybe enough to make recovery more difficult resulting in one.

Race car drivers try to maintain equal tire traction and weight balance for valid performance and safety reasons as recognized by the rules committees. Why we continue to second guess the experts whose lives depend upon it, I’ll never know. Maybe we think we’re immortal or have made the choice that economics trump safety when financial situation is tough. Fine…but don’t tell me it’s safer.

The rusty dodge above the article had all seasons on the front and snows on the rear. Read what Peter says about stopping. I know it sounds unlogical but you should try it.

I don’t think I read you wrong. The idea behind all treads being the same is that there will always be a traction difference if not. Snows on back may mean better traction in rear in snow, but could be significantly worse on dry pavement and in rain if block tread design or poor rain performance which is often the case with cheaper snows. Studded snows can even “skate” on dry pavement when new.

In the case of worn tires on front, generally they can have “better” traction on dry pavement, again with rear new tires having less. Enough of a difference to “cause” loss of control. Maybe not; but with respect to your general assertion avec FWD, maybe enough to make recovery more difficult resulting in one.

Race car drivers try to maintain equal tire traction and weight balance for valid performance and safety reasons as recognized by the rules committees. Why we continue to second guess the experts whose lives depend upon it, I’ll never know. Maybe we think we’re immortal or have made the choice that economics trump safety when financial situation is tough. Fine…but don’t tell me it’s safer.

New tires have less traction!!!The tires on the front get over twice as hot and become harder faster than the rear plus the sharp edges are rounded quicker.
On a fwd every time you rotate front to rear you slightly increase your chance of an accident.
Four identical tires on a 60/40 weight ratio fwd . If you are driving at 60 mph and you feel the front start to hydroplane you might not be aware the rear started to hydro plane at 40mph. If the front tires wear you will feel the hydroplaning start at a lower speed. But still faster than the rear. If you rotate the front tires will now hydro plane again at 60mph but the now worn rear will start to hydroplane at a lower speed , say 35mph?.
When I look at the knowledge and expertise available on this site I find it quite impressive. They make more sense than some engineers I have encountered.

Pssst . . . Hey Harvey, Got A Minute ? You’re Into Tires, Traction, And Hydroplaning.

Did you ever read my old hydroplaning story ? Here’s the link. See what you think.

http://community.cartalk.com/posts/list/2119076.page

What’s your theory ? What was going on there ?

CSA

CSA yes that sounds like hydroplaning and on rear engine car you need very good traction on the front to prevent understeer.
You want to try something scary put a fwd on a wet skid pad with older tires on the back. You can put on the park brake and the car won?t even slow down.
If you follow a fwd on very wet roads you can sometimes observe the rear of the vehicle drifting left and right. If you watch the front they will seem to be solid on the road and not turning left or right on the surface. What is happening is the driver is steering by using the rear as a rudder. Scary!
Watch Michelins rear tire video and slow it down when there is a front on view of the blue car. You can see this happen clearly

'New tires have less traction!!!The tires on the front get over twice as hot and become harder faster than the rear plus the sharp edges are rounded quicker. " [b]Harvey

Consumer Reports says newer tires having less traction on dry pavement !
“Better dry-road performance. Bone-dry pavement is one place where less tread means more grip, since shallower grooves and sipes put more rubber on the road. That’s why mega-horsepower racing cars typically run on treadless “slicks” for all-out traction. It also explains why the half-tread tires performed better in our dry-pavement handling, cornering, and braking tests.” [/b]

That would make new on rear with with big difference in tread depth, more of a problem ! Again, everything points to “keep them close”.

Yes if you read all consumers reports or any other reports but they try to lump all cars together. Did you ever see a report that seperated fwd ,rwd ,etc. When you have 500lb or less on a tire the edges and softness of the tire become very important.

PS, I use the front to rear, same side and rear to front opposite side method with good results. There are other patterns but I have not used them; can’t comment on them.

CSA,

I don’t know if I would use the word “slush” and “hydroplaning” in the same sentence, but conceptually that is what is going on. While you didn’t say so, I imagine that when you drove onto the slush, the speedo would gradually drop to Zero, while when you came off, the speedo jumped up to speed.

I’m guessing that the friction of the bearing (and perhaps from brake drag) was higher than the friction being generated between the tire and the slush and that’s why the speedo stopped.

I also think you demonstrated that even with only one tire on dry pavement, there is still plenty of traction to maintain direction - and the lesson we should take from this is that tire traction is bountiful in the dry, but it’s when the conditions are poor that we should consider when deciding what to do about tire placement.

Just a reminder that every tire company,safety organization,driving school, and transportation authority says " new tires go on the rear if only buying 2

New tires on the rear may be true so why does your owner’s manual not say this? I think that there may be a slight advantage but it is not critical to put new tires on the rear. Tire changers etc. are afraid of lawyers taking advantage of the slightest doubt.

Please supply information, if you can, to show that everyone of the organizations named are not just repeating what someone else said.

What do those people say about rotating tires after which the new tires will be on the front? Tires wear very slowly now and so it does not matter if new tires go on the front or the rear.

I don’t worry about rear tire hydroplaning and this was said before, by Caddyman I believe it was, the fronts clear a path for the rears while going straight ahead. You are supposed to slow for sharp curves and corners and your experience and senses will tell you how much to slow.

just put it in a search engine " put new tires on rear" The last authority to say put them on the front was an author on msn. I have the appology for that one and they changed it immediatly
Largest lawsuit 32.4 million , dealer put new tires on front

Time for tort reform-Kevin

The part where you keep it simple remains obscure.

“Just a reminder that every tire company,safety organization,driving school, and transportation authority says " new tires go on the rear if only buying 2”

It’s the lesser of two evils…do you doubt that bald/worn tires have better traction than new tires on dry pavement ? Do you doubt the validity their tests ? They are testing tires, not cars, and the results are consistent with ALL cars. Bald or worn tires have better traction on dry pavement. What’s so hard to understand ? It’s a commonly known fact. It’s just that in the most demanding conditions with larger traction differences occuring in inclement weather…when the lawyers are out and why better on back is recomended.
The key word is “if” two tires are bought which is never as safe to begin with as buying all 4. Buying two and not 4 is a $$$$ decision, not a safety decision.

The tire companies have been saying new to the rear for 30 years that I know of. Maybe it just takes that long for the public to learn. I know it was in the course for auto mechanics I took in the 70s

Driving with bald tires is just plain stupid and should not be a factor in the discussion.

Who said they should be ? Badly worn/bald tires have so many deficiencies, they should never be used,but lack of dry pavement traction IS NOT one of them…

It’s a discussion on traction with respect to why race cars run slicks (like bald tires) for maximum traction, but only on dry pavement.See CR comments above.“Better dry-road performance. Bone-dry pavement is one place where less tread means more grip,”

To dismiss this analogy as that alone is in your words “just plain stupid”. If those technicalities allude you, I apologize. Please read everything in context and not pick out just one post in the discussion.

This is not a racing forum and I, for one, do not have a handle on when racing analogies apply and when they do not apply to the streets and highways.