cclcal

Question is do I have to replace all 4 tires simultaneously.
I had 1 bald tire and 2 that were a little past the wear indicator.
4th tire was excellent, just replaced due to road hazard. Spare is close to bald too. 2 were Pilot A/S, two were Pirelli Rossos.

Discount Tire said I had to replace all 4 at the same time due to quatrro system, if I don't it will ruin the car.
He asked who changed these tires before, I said "you did."

I ended going with 4 new ones, Yokohama YK580, better tread life. 580 and 60K mile warranty. Tire size 255/40/19. I'm in SoCal so no snow, barely any rain.
He credited me 230$ for the newer tire.
So 948$ out the door. Good deal for me.

Still not sure I needed all 4, 3 would have been fine I think.

Opinions?

thanks!

mishar

Continental ExtremeContact DW. Keep the good one for a spare.

You do not have to change all four of them at the same time, but in the case of four bald and one good that seams your only choice.

cclcal

thanks. That's what I thought too. The guy is trying to make a few extra hundred bucks.

Those contis are nice too, treadlife is short, i hate spending 1000$ so often.

volvopentaman

The quattro permanent 4WD system requires a certain amount of consistency between the tire sizes, due to it's purely mechanical nature. If you put different tire sizes, it will cause wear on the driveshafts and differentials.

A small change in wheel diameter (=worn tires) isn't a problem, but the bigger problem is that if you have let's say in your case one tire different than the others (another brand/model) it will cause driveability problems. By this i mean that the car can behave unexpectedly in extreme situations, due to different traction on the different models of tires, and even due to that one tire is older (and the rubber has hardened over the years). Another problem can be that some tires are "softer" than other, so you might get a weird feeling, mainly on the highway, and the car might start to "wander" and you loose the perfect ride feeling.

At least here in Finland it's legal to use any model/make of same season tyres together, as long as they are the SAME size on the same axle.

So i CAN use:
255/45R18 at the rear conti sc2 + 245/45R18 Michelin Pilot front (tested this, no problem under 6000km and around 270km/h speed)

I can use the same size but different brands on separate sides of the car.

M+S STUDDLESS front and summer rear and vice versa.

I can NOT use :
255/45R18 on one side of the car, and 245/45R18 on the other.

Studded tires together with studdless

I once replaced 205/55R16 Conti SportContact2 tires on my Volvo S90 -98 with Michelin Pilot's, same size that were ment to a Honda Accord 2005 (new tires of course). The ride quality was much more unprecise with the michelins, so i suspected something. I used 2,6bar at each tire as recommended, but then i measured the tires. The michelins were MORE than 1" (2,8cm) narrower than the conti's, enven tough they had the same advertised size.

Conti's really seem to wear fast, but otherwise they are excellent tires, as are michelin Pilot Sport's also. I can also give my support to Kumho's Ecsta Supra tires (i think they don't sell them anymore), and i've heard good about Yokohama and Toyo too. I think my next bet are Kumho's for the A8, i was very pleased with them on my both volvo's (S90 and 340 -86 with 225/40R18 and 225/45R16).

Flats

Having trouble with my 07 A8, it is eating tires especially the rear passenger side, got 9000 mi out of my 1st set of Conti's...Took it to an alignment shop that uses Hunter equipment and bought a new set of Conti's that have a 30k warranty and the rear passengar is still wearing more than the other 3. Shop says every thing is fine; tie rod etc..the last time they rotated them they crossed em....won't that change the traction of the tires & has anyone had this alignment problem?...Thanks for the response...Flats

mishar

Mixed and mismatched tires discussion doesn't really belong on the luxury car forum.

Only reason that a tire on a certain corner wears faster than others is bed alignment. So second opinion needed if one shop can't find what's wrong. Rotating and especially crossing tires is to conceal uneven wear. On many serious cars it is not possible because of different sizes and directional tires.

volvopentaman

Yes, as mishar said, only reason that car eats tires is bad alignment.

Alignment can be easilly measured yourself with a measuring tape and a spirit level.

You need to have tires like conti sport contacts that have "grooves" all around.

Put the car on a level surface with NORMAL DRIVING HEIGHT on, not "lift" from the MMI air suspension! It's critical that it's in normal driving level, otherwise the alignment angles will be a bit different.

Then you take your measuring tape and a buddy, put the tape in the groove of the front of the tire (car driving direction wise) on one side, and the same groove on the other side tire, and take a reading.

Then you put the measuring tape on the rear side of the tire and take a measure. The rear side shoud show 2-7mm more than the front. If it's NOT in this range, you are off the alignment. Do this for both front and rear axle.

This is called "toe-in" measurement.

Now for this step it's crucial that the car is on a level surface.

Take your spirit-level, put one end of it against the RIM's lowest point heightwise, and level it vertically, and measure the gap between the upper end of the rim to the level. This reading should be around zero. If there's a huge gap (1cm++) you are off alignment. A few millimeters is OK. Do this for all wheels.

This measure is called the camber measurement. You measure the angle of your rim towards the height of body of your car.

I've aligned all my car's this way, and no problem with tyre wear.

Or, except my old Volvo 340 with a solid rear axle (no adjustment possible except bending), that has been punished with 450hp/700Nm for the last years, and has a camber of like 2cm per side in the rear, but either way the tires are OK after 15000km.

A professional workshop has an laser alingment system that is far more accurate than my measures, but if the user is a goof, that will spoil the alignment.

mishar

This alignment method is very inaccurate (you can reach groves at a very low point, groves are not parallel enough) and your tolerances are far to big.

By the way how do shafts work with 2 cm camber on a solid axle when differential axes and wheel bearing axes are not aligned?

K9COP

We use two piano hinged pieces of wood about 5"x20" with metal 'L' section edges on them on the race car to do the alignments, and measure across the car at various points, then check with camber gauge etc, but as mishar says, not 100% accurate. Good enough for an ancient 911 though. But what I would suggest, is checkout www.hubstands.com it's a system to adjust all the various wheel parameters, such as camber, toe in etc with the wheels off, but the car on the floor. Very basic explanation is 4 'gimballed' plates and bases. I know the guy who owns the company, Brion Charters (real nice guy) so if you need a contact, shout me up. Not cheap, but very well made, and very effective. Or maybe just check the website for interest....

volvopentaman

As i said, the method has worked for a long time, done dozens of cars like this, and so far no problems with tyre wear. The accuracy is within 1-2mm, so enough to adjust toe-in, as the toe-in is normally 4-6mm so 1-2mm suffices nicely.

I even had a toe-in adjustment tool like this:
http://www.chicagolandmgclub.com/mem...alignment1.jpg

The accuracy with that was the same as my measuring tape method.

But undoubtly, a laser adjusting appliance is the best way to do it. But i meant, that if the starter of the thread has such a bad mechanic, that he can't check the alignment, here's a simple method to DIY.

And as you don't seem to know a volvo 340 (wasn't sold in the US), it has a De-Dion type solid rear axle, with floating driveshafts, here's a pic:
http://i1.tinypic.com/4mahkiw.jpg