Buying & mounting new tires tomorrow (two questions)

dags. easy.

and when you figure it out, you can then go ahead and ignore it. as soon as a wheel is used and has mounted a few curbs, even if there's no apparent damage, the whole alignment equation changes, so it's pretty much a pointless exercise. which is why you'll find some of the smarter manufacturers don't bother with it. [and of course, if you make a good tire in the first place, you're close to balanced anyway.]

imo, traction ratings are utter b.s. and are no basis on which to base a buying decision. i had a set of aa-rated dunlop sports on one of my cars. even new, they hydroplaned so ridiculously bad in the wet, you couldn't do much more than 50 if there was actual rain [as opposed to just a wet surface].

the only brand [but not all models of] tire i've ever had that inspired confidence both new and worn, wet or dry, is michelin. other tires are better dry. others are better wet when new. but nothing in my experience comes close to acceptable wet or dry, all stages of the tires [legal] life. [disclaimer: i don't "do" snow.]

Here's an explanation from Bridgestone:

Agreed, it's all in how it drives. If the tire guy in conscientious and has a good road force balancer what he'll do is mount it with the dots oriented right as a starting point and then break loose/rotate the tire to fine tune it. So the dots may not be in the right place, even if the guy is doing it right.

That said, I think that most tire mounters just put the tire on any old way (at least they usually get the rotation direction correct) and then balance them the best they can and send you out the door.

I agree w/ Michelins being excellent; another tire I've had good experiences with is the Yokohama AVS ES100, Michelin having discontinued tires to fit my old 944. Unfortunately the Yokohamas suck worse than you could possibly imagine in the snow, but they aren't even M&S rated, so they never pretended to be an all-season tire. I had a set of Dunlop Winter Sports for that, and those worked great.

nate

SF Man wrote in news:j3kfbf$agk$ snipped-for-privacy@speranza.aioe.org:

If you have to tell them how to mount tires, you shouldn't be going to them.

These dots are used for mounting the tires so they spin true. Tires mounted to spin true will not wobble, squirm, or hop at the tread when they are spun. True-mounting is 100% critical to proper balancing technique, and few tires monkeys know to do that. You cannot balance the tires until they spin true.

But even before that, the monkey needs to spin the wheel on its own, and to spin it in two opposing orientations on the spindle, before he knows where the high-spot and heavy spot of the wheel are. He needs to know this information when mounting the tire.

And the tire dots are used as a STARTING point. You may need to rotate the tire from the starting point to get it to spin true.

You can ask your prospective supplier these questions:

1) Do they use the yellow and red dots on the tire? 2) Do they use the dot on the wheel, if they can find it? 3) Do they use proper tire-mounting paste? 4) Do they check to make sure the tire spins perfectly true on the wheel (no wobble, squirm, or hop at the tread) before they balance it? 5) Do they phase-mark the tire and wheel before you leave, and make sure you understand to avoid hard acceleration and braking for a few days to allow the tire to "set"?

If you get a "huh?", or a "we don't do that", or an "it's not necessary", walk out of there.

Make sure the tire shop has a Hunter Force Balance machine. Many shops do. I think it's standard at Just Tire shops. Then forget about the dots. Meaningless when force balanced. For the rest I've had good luck looking at the tire reviews on Tire Rack. If there are enough reviews for the tires you're looking for, and on your car. Without a lot of reviews giving decent info it's a crap shoot.

--Vic

great machine. almost impossible to mess up a balance with that thing.

indeed.

make that "customer reviews who have driven them for a few thousand miles"

you can't rely on tire rack's system ratings. i bought a set of continentals that were highly rated per their star system, and they were perhaps the worst tires i've ever driven. they were kinda-sorta ok in the wet when brand new, but a few thousand miles in they were skate shoes, and dry traction? practically non-existent. my 89 civic is one of the better cornering cars on the road, and certainly tire width for tire width. on the twisties, with decent standard width tires, she'll not blink at bends that have much more expensive cars with much wider tires braking to approach. with the continentals, she couldn't keep up with other cars on the approach, and once you were in, she'd often crab sideways because they'd start to slide. and straight line braking? if you locked a tire, traction dropped to almost zero. i've never known that on a tire before. on all tires, sliding reduces stopping ability, but other tires are not the greased banana skins the continentals were. very misleading tire rack rating.

tire dots are irrelevant if the wheel's balance points are not known. if the operator identifies the balance of the un-tired wheel, only then can the tire dots be aligned to anything.

some tire manufacturers don't use dots. michelin for example. and michelin /know/ tires.

they shouldn't even /look/ for a dot on the wheel - completely unreliable unless the wheel is brand new. the wheel should be spun and its balance assessed entirely independently.

if a tire is that bad, it should be mounted, inflated, and balanced a couple of days later because any initial balance will change.

if you go to a decent shop, with decent equipment, and you're buying decent tires, you can forget worrying about this stuff. and if you're trying to make a silk purse out of a sow's ear, no amount of "dot alignment" will help you. garbage tires are garbage tires. period.

Exactly. You need some thorough customer reviews you can trust. Once you find a tire with a reviewer that has the tire on your car or similar enough, click on the "more tire reviews for this vehicle." That opens up a range of different brand tire reviews for your car. You just end up winnowing them down. Takes a while. It's worked for me, and I don't know where else you can get this kind of "real" experience. Judging what reviews to trust might trip some up. And then you find some tires discontinued so you do it again.

I never paid any attention to the star rating, just the reviews. Seen a lot of mention of cornering, traction, noise, wear. I favor traction, noise, and wear in that order. Fast cornering isn't my style.

--Vic

--Vic

Very interesting!

"if the tire has a red dot, ignore the yellow dot. Then, if you have a steel wheel, look for the low point dimple on the wheel, and mount the tire with the red dot next to the low point dimple. If the wheel is aluminum, or if it?s steel, but has no low point dimple, mount the tire with the red dot next to the valve stem"

"Regardless of the type of wheel, if there is no red dot, mount the tire with the yellow dot next to the valve stem."

That pretty much explains it!

Thanks for digging that up.

I wonder how many people know this?

Every few years, I get tires mounted.

Every time, I ask them to mount them properly.

Almost NEVER do they even KNOW about the red/yellow dots.

I know about them ... but I always forget which one is the heavy spot and which is the light spot ... and which goes across from the valve and which goes next to the valve (on aluminum wheels).

These are Big-O, America's Tires, Goodyear type places. So, I think NONE of them know how to properly mount tires. :(

Doesn't it enable less weight to be used?

Doesn't it allow less weight to be used?

I bought the tires 'by the numbers'.

Tire Rack had about 40 tires that fit.

So I whittled down the list to one tire by assessing:

• Size = same as original

• Traction = AA only (wet)

• Temperature = A only

• Treadwear = the bigger the better

• Speed = the higher the better

• Load range = the higher the better

• cost (including tax & shipping & mounting & balancing & disposal)

I 'wish' there was a way to assess dry traction and road noise ... but as far as I know, there are no tests that you can find for 40 tires to compare.

The tire rack reviews seem to all be written by high school dropouts, by the way - so, for the final three tires, I did read the reviews, but it was a waste of time. They were all good to some degree or another.

sure. and you can "balance" a square wheel too. but if the wheel is not round, or the tire is not round, or even has different tensions in the cordage, the wheel will never "feel" balanced on the road, no matter what you do.

even if you pay attention to the dots on the tires, it's pointless trying to align them with valves or dots on the wheel unless the wheel is brand new. once it's been on the road, and run a few potholes, a few curbs and generally "lived a little", its balance will have shifted. thus, given that most of the big shops use good quality balance machines that take this into account, you're more likely to be witnessing the tire being aligned to the wheel's /real/ heavy spot than anything else. and if you're getting a negative reaction to your questioning, what would the reaction be from your dentist if you started questioning their practices? do you know more then them? tire shops don't ignore stuff just so you can come back, bitch, and cost them money in warranty work.

the bottom line is whether the wheel drives balanced or not. if it doesn't, maybe the shop didn't do it right, but maybe you have a square tire. if it drives well, wtf are you worried about?

I guess I'm confused. These tires I bought cost $185 each.

I don't 'think' they're 'garbage' tires, as you seem to be suggesting (unless I misunderstand your kind reply). All I'm asking is where the red/yellow dot goes when mounting, because the tire mounting guys often don't care (I've seen this happen every time I get tires mounted). They assume you don't know that the red dot even exists!

Here's the answer, thanks to a previous poster in this thread:

"The red dot indicates the ?radial force variation first harmonic maximum.? That?s a mouthful, of course, but it?s a way of indicating where the centrifugal force tending to pull the rotating tire away from the wheel is greatest.

Another way of looking at it is that in a sense, if the tire were out of round, the red dot would more or less correspond to the ?high point? or place where radial runout forces are greatest.

Why not just measure the runout of the tire?

The radial force variation measurement is much more accurate in predicting tire behavior. In fact, the red dot often isn?t located exactly at the ?high point.? Instead, it accurately marks where the runout-like force is greatest.

But, if you think of it as marking the tire?s ?effective? high point, it becomes pretty obvious why you?d match the red dot with the steel wheel ?low point? dimple. It?s as though the tire is a bit ?thicker? (from wheel to tread) in the red dot area.

And, since the dimple marks the low point on the steel wheel, you might say the wheel is a bit ?thinner? (from axle to flange edge) where the dimple is.

And on aluminum wheels?

At the red dot location, the tire is trying to pull away from the center of the axle a little bit, as a result of higher centrifugal force.

As in our last example, it?s as though the tire is a bit ?thicker? near the red dot, which has the effect of pushing the wheel and axle upward as the red dot gets to 6 o?clock.

Meanwhile, the fact that the wheel is a bit heavier at the valve stem location generates a centrifugal force effect trying to pull the axle downward as the valve stem gets to 6 o?clock.

Those forces tend to counteract each other.

And the final result?

Matching the dots is no substitute for balancing tire and wheel assemblies. What it does, however, is give you the best start, so you are more likely to use less total weight to bring an assembly into balance.

Since the red dot indicates where the tire behaves as though it has a high spot, at the 6-o?clock position, the road is pushing the tire upward, while centrifugal force from the wheel heavy spot is trying to push the wheel downward. These forces tend to counteract each other.

The only asymmetrical hole bored into aluminum wheels is the hole where the valve stem will be mounted.

A typical valve stem weighs about 1.2 ounces more than the aluminum that is bored out of the wheel where it is mounted.

The red dot marks the maximum point of radial force variation, and behaves as though it were a ?high point? on the tire."

i guess i have to say it again - they're probably mounting in accordance with the /real/ dynamic weighting of the wheel that has been /driven/, not per the "guess it's balanced" approach you can use with a new wheel.

>

why not indeed. but now you've measured it, what are you going to do? bend the wheel so the tire's round? at what speed?

at what speed? harmonics can move that thing around. ask anyone who has balanced helicopter rotors.

you're giving much too much credence to dumbed down pseudo-tech sales crap you read on the net. take the tires to a shop with a decent balance machine like a hunter, and stop second-guessing people like its designers who are good at math and have analyzed the problems in exhaustive detail.

Good point.

I don't know more than they; but I still want my tires mounted properly.

The manufacturer doesn't go to the trouble of putting the dots on the tire for no reason at all (do they?).

Unfortunately, after reading the PDF that someone referenced in this thread, I now realize the yellow and red dots are vastly more than just a 'heavy' spot or a 'light' spot.

For example, witness these quotes: "The red dot indicates the ?radial force variation first harmonic maximum" with the result that "At the red dot location, the tire is trying to pull away from the center of the axle a little bit, as a result of higher centrifugal force".

So, I printed it out and will bring it to the tire shop because the last time I had tires mounted, they told me they never heard of the red dot (that was at Goodyear, btw).

I showed it to them on all their tires, and they said they've never noticed it before. So, I just wanted to check, ahead of time, where the red dot goes.

Thanks to that PDF, I have the answer. It's the right way to balance a tire & wheel assembly.

Force balance does that. My kid did this for a couple years at Just Tires. The machine determines where to rotate the tire on the rim. He said the dots seldom match what the machine says. Seldom enough to be random.

--Vic