CBR2200

They are directional so reverse mounting them is a no go. That was my first thought as I used to do that on my track car that I ran with high negative camber. The recommended pressure on my 550 is 35/42 front/rear. I've played around a little with the pressures. I've been happy at around 38/45.

will_w204

I guess the larger tires run a higher pressure. Mine are recommended 32/32-38

Pay attention to that higher rear number - it's only under full load. I made that mistake when I got mine, and the rear end felt like it was gonna bounce into the sky over bumps. Running 32/32 now.....unless I'm hauling a load.

.....and as to the idea of reverse-mounting non-directional tires to get more out of them....is this technically and feasibly sound as a tire maintenance procedure in this situation?

drgeeforce

Reversing tire direction was a common practice in bias-ply tires to even out the wear in non-radials. The appropriate use of radial ply tires is to keep the cords/carcass rotating in the same direction. This is because during use, heat causes the radial cords to "lean" in a direction after a couple thousand miles, kind of like the grain of the wood. Turning the tire around to run in the opposite direction will cause premature wear, as the tires are rolling "against the grain", they will wear out rapidly. Proper wear rotation is from front to back same side only and from back to front.

BVLDARI

I have the scorpion Zero and they suck. Any advice on how to approach Pirelli to get them replaced - I would be happy with a set of P Zero which should make them a little more interested in replacing for me I would think?

N_Jay

You still cross rotate non-directional radial tires.


Belt shifting was blamed for early radial tire failures, (Back in the Firestone 500 days) but I don't know any non-directional tire you can't cross rotate.


http://www.tirerack.com/tires/tirete....jsp?techid=43

drgeeforce

N_Jay: if you read carefully, the tire recommendations are ideally to maximize wear on all tires so that they can be replaced at the same time. The cross pattern will cause premature wear on all four tires, hence the dissatisfaction with most drivers getting sub-20K on UTQG 30K service life.

UTQG rates tires to give a semblance of expected wear life on tires given similar driving conditions. If most drivers follow a front to back and back to front pattern, you will find the UTQG numbers matching actual driving numbers. I follow the F to B and B to F, and I always get 35K+ per pair of 30K rated tires. Granted I don't do two-wheel dragstrip launches and I don't do hockey stops. I have never replaced all four tires at the same time, I usually replace pairs when I see the wear bars on the tire tread. I do have some reservations about cross pattern rotation on assymmetric non-directional tires, I find the grooving to be somewhat similar to directional tires.

Cross pattern rotations, although the method is altruistic in nature, it benefits the tire companies more than the consumer. Yes you get optimal performance from the tread as it wears down, but how many of us GL350 drivers actually do rally racing and "performance" driving? If I wanted to do a winding road full of S-turns, i'll take a coupe or a sportster.

N_Jay

Do you have a reference for your beliefs?
. . . . Because doing cross and back rotations I got 65K miles from the factory fit tires on my Pilot and 100K from the Michelins I replaced them with.
We also got 55K from the tires on my E-350 4-Matic Sport (Still with tread until an alignment issue killed 2 tires so I did the set)

DarthVaderpa

Keep in mind that you're driving a 5500 lbs car (not including driver, passengers and luggage)! Mine is a GL450 (5300 lbs) and I found that pressure is definitely a big factor. I replaced the fisrt set of Contis after driving barely 30K using 38psi. I got a new set of Contis (because I installed them at MB dealer and they only approve Pirelli or Conti for my GL), set the pressure to 32 psi and adjusting the rear to 38 when I loaded the car. After 12500 miles of serious driving (sun, rain, and snow: went from FL to NC, the NC and back to FL) tires still are 65%. I use nitrogen and rotate them every car service (13K). For alignment I use MB dealer because they offer the full alignment (four wheels).
There are some other options for 19" but MB only approve Pirelli and Continental. I know some dealers have Dunlop SP Sport Maxx, however the tire is only good for summer.

drgeeforce

My beliefs are derived from experience. I have performed rotations on bias-ply tires, radials both directional and non-directional, and I have to admit I don't know those driver's habits. I do see from the numbers of tires replaced, cross-rotation pattern drivers are replacing their tires at a lower mileages. My shop follows the cross rotation recommendations by the manufacturers, but on my personal vehicles, I follow the front to back patterns.

Tires that are UTQG rated 800 and above, getting 100K+ miles, are becoming more common on the roadways. Attributing cross-rotation to this high value is suspect since you didn't try other rotation methods.

N_Jay

The 100K were CrossTerrains (I think) rated about 500 (Circa 2006).
The 55K tires on my E were from early 2010 (Certainly rated under 500)


So let me understand, all documentation recommends cross rotation, and I have gotten exceptional life.
Yet, you have received average life from front-rear rotation, and you think I may have just built myself a myth?????

will_w204

I have a theory that PSI in light of the sheer weight of this vehicle is a critical factor, but your statement of "dead at 30k with 38 psi" and "still at 65% with 12,500 at 32 PSI" looks like the exact same result to me

N_Jay

Seems counter intuitive.


Usually higher pressure (up to the tires design limits) yields better life.

will_w204

The point of my reply was math. He said he got 30k out of OEMs at 38psi. Then said he was getting "better' results, "better" calculated by 12,500 miles of driving at 32psi, and 65% of tread remaining.

That calculation would mean the tires would be worn out by 30k, exactly the same as the OEMs at 38 psi, which would seem to indicate 32 vs 38 makes zero difference whatsoever in tire life.

Again, I'm just making a point with his calculation. I would like to verify that a 6psi difference in pressure may make NO difference AT ALL in tire wear, or if that was a mis-statement

N_Jay

OK, misread your post.


There are so many variable to tire life that it is easy to build myths.


I have consistently found much better than typical life (and I drive fairly hard) by doing the following.


1) Keeping the tires at the highest pressure I feel is safe. (Hard until the ride becomes noticeably bouncy)
(Usually 4 to 8 PSI above recommended, always at least 2 PSI below sidewall rating)
2) Cross Rotating regularly.

It might be a myth, but in 30+ years have never had a set of tires not go at least 40K (That was about all I could tease out of an old Range Rover) unless it was a alignment issues (F-ing Ford Company Car) or road hazard failure) 100K is my record.

will_w204

I have found the same things as you running higher than listed pressures in 15-18 different cars, but this car at 5300 lbs on street tires seems to be bucking every bit of conventional and seat-of-pants wisdom that I've gleaned from 22 years of driving.

N_Jay

So far I an getting about what I expect.
Bought it with 3/4 used tires (Two replaced due to road damage) and now that it has another 18K miles, the other two are ready for replacement.
The two with about 16K miles look very good. (It is a GL320, so I am not ruining as wide a tire.)


P.S. About 4+K of the miles were towing.

drgeeforce

Michelins are excellent tires, even though rated at 420. Your case exceptional? maybe not. Google Michelin Cross Terrain you will find these tires often go past 100K.
http://gmtnation.com/forums/topic/54...rains-at-130k/

N_Jay

I think you are missing the point.


Proper (cross) rotation is what most people do. How do you support that non-cross rotation provides better tire life?

drgeeforce

Again, from experience. How do you support that cross-rotation DOES extend tire life. Just because "everybody" is doing it, doesn't mean it is the right thing to do. Just like you I cannot provide any study that proves it does or not. I go by my 12 years of shop experience, seeing worn out, toe and camber mis-alignments, shocks gone, cupping, re-tread failures, stiletto to the sidewalls, and my ASE A9, L2. Certain items that are mid-late consumables, like tires, coolant, transmission oil, etc. have an expected run duration. Anything in the name of "safety" that shortens that duration is generally accepted and profitable. Yet I often find a few high mileage vehicles that have never had a transmission fluid change, or better yet, never an engine oil change, the customer kept adding a quart or two every six months. That's what I call a no-brainer.

This article kind of explains my standing:
[Tire rotation is a simple matter, but like many things automotive it is also loaded with mis-information. The principle is to even out tire wear, between the front and rear of the vehicle. Tires are normally rotated between 5,000 and 9,000 miles. In theory this should provide longer tire service and there are four patterns in general use.] http://www.agcoauto.com/content/news/p2_articleid/94

If anyone can find a SAE publication advocating that cross-rotation tire patterns provide exceptional mileage, i'll make it into a poster and hang it in my garage.

N_Jay

So let me understand.
1) Just about every source recommends cross rotation for tires that can be. (Tire companies, Car companies, and Oil companies, and the government)
2) You have produced exactly ZERO links for your suggested rotation method.
3) You only will accept an SAE recommendation to concede you might be incorrect.

Do I have that right?

N_Jay

SAE seems not to have anything on the web, but what about the NHTSA?
http://www.nhtsa.gov/cars/rules/tire.../brochure.html

drgeeforce

If you believe everything the government says....

The Society of Automotive Engineers is the Gold Standard. Care to wonder why they don't advocate ANY particular pattern?

N_Jay

I work with an industry standard group. There are lots of things unsaid.


I find your proof being the absence of a statement from one group as "interesting".

BVLDARI

So is there a consensus on which 21" tire is best for this thing? Anyone try the Continental ContiSportContact 5 SUV ???

DarthVaderpa

I made a mistake when measuring tire threads, after 13,500 still at 70%.
I know it's not a great result, but considering that the Conti 4x4 Contact has a really bad treadwear, I think am getting a "not to bad" results. I would like to try the Conti CrossContact LX20 but it isn't available for the size I need, 275/55R19.