Match Mounted Tires & Wheels

4

427435

Senior Member
I noticed that the little dots on the tires, that are normally lined up with the valve stem, aren't lined up on my car. Doing so is supposed to align the high spot in the tire circumference with the low spot of the wheel. There is no tire vibration, and there isn't much balancing lead on the inside of my wheels either, but I'm wondering why the factory didn't match mount the tires onto to the wheels.

Has anyone else noticed if their tires/wheels were match mounted?
 
427435 said:
I noticed that the little dots on the tires, that are normally lined up with the valve stem, aren't lined up on my car. Doing so is supposed to align the high spot in the tire circumference with the low spot of the wheel. There is no tire vibration, and there isn't much balancing lead on the inside of my wheels either, but I'm wondering why the factory didn't match mount the tires onto to the wheels.

Has anyone else noticed if their tires/wheels were match mounted?
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On a steel rim that is designed to have a wheel cover, the rim is measured to find the low spot and the valve stem hole is then drilled at that location. Our rims are not done this way, the stem hole can only be in one of five possible locations, so indication of the low spot is done on the back of the rim.

Some manufacturers have an arrow stamped on the inside of the rim, typically on the flange area, that points to the low spot. I do not personally know for sure this is what is done on our rims but either that or some other indicator is used on all but the highest quality rims, those that have nearly perfect rims as far as runout is concerned.

I think I remember that indicating the low spot, if runout is greater than a certain standard, is a requirement for the DOT approval for the rim.
 
Some manufacturers have an arrow stamped on the inside of the rim, typically on the flange area, that points to the low spot. I do not personally know for sure this is what is done on our rims but either that or some other indicator is used on all but the highest quality rims, those that have nearly perfect rims as far as runout is concerned.
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Our wheels are high quality, forged and machined. It is not beyond reason that they are nearly perfect as far as runout is concerned.
 
I have always been sure to line up the tire with the valve stem for decades. Just something I got into the habit of doing. Just cheap pece of mind I guess.
 
Ford does match mount all tires and wheels. They have monster machines that mount, match, and inflate in an incredibly quick process. That said, the low spot on Ford wheels isn't necessarily always at the valve stem. On two of my wheels, the correct point was almost opposite the stems. Your car should have come off the truck with flourescent tape marking the wheel match point. The dealer is supposed to remove the tape as part of prep.
 
Sounds plausible to me Pantherman but I think DOT rules state some permanent indication is required.

Anybody got their wheels off now to go check?
 
Pantherman said:
Ford does match mount all tires and wheels. They have monster machines that mount, match, and inflate in an incredibly quick process. That said, the low spot on Ford wheels isn't necessarily always at the valve stem. On two of my wheels, the correct point was almost opposite the stems.
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On all of my tires, there is a red marking (circle) just opposite of the valve stem. I guess they're all matched.:confused:
 
Come again? This is the first I've ever heard of this. I find it very interesting as I have been having one hell of a time getting my wheels balanced. I bought new tires, and had BFG replace them all under warranty because they all failed the road force balance. I did find it increadibly odd that all four were defective. Wheel runout was just fine. As of right now, I still have one tire that is way off balance. Can anybody get a definite on the accuracy of this thread? And if so, a definite on where and how to properly mount.
 
The red dot is the high spot on your tire as determined by the tire manufacturer during a final phase of the tire build, a step where the "concentricity" (roundness) of the tire is measured. The wheel also goes through a similar process, only the low spot is found on the wheel and a grenn sticker is applied. When the two arrive at the assembly plant to be mounted, this is where the term "match mounting" comes in. The red dot on the tire and the green sticker on the wheel are lined up giving the "most round" contact to the road to reduce wheel/tire vibration due to raod force. Once the green stickers are gone there is no way to know if they were match mounted properly, except to re-measure the wheel.

Unfortunately, the dealership equipment used to determine you tires were defective for high road force is not nearly as accurate/repeatable as the equipment the tires manufacturers use. So the bad news is the likelihood you got non-concentric tires from the plant is very low, and unfortunately the likelihood you got worse tires on warranty replacement is much higher since the tires the dealers and tire shops get are the ones that got kicked out of the process above but were still acceptable for sale to the general public.
 
Has anyone inspected the back side of their wheels to see if there's a permanent mark on the wheels? The dots on my tires are every place but next to the valve stem. If the wheel low spot isn't at the valve stem hole, as someone posted, (and with the spokes the valve stem hole can't go just anyplace) then perhaps we should stamp a small mark on our wheels across from the red dot on the tires---------before the red dot is worn off. That why replacement tires can also be match mounted.

Just thinking ahead a bit---I plan on keeping this car a long time and the tires will need replacing more often then with most cars.
 
Perhaps we should stamp a small mark on our wheels across from the red dot on the tires---------before the red dot is worn off. That why replacement tires can also be match mounted.

This is an excellent idea, assuming your tires and wheels were properly matched originally. If your car was smooth new, you can probably trust that to be the case.
 
That would work if your next set of replacement tires came with a high point mark, but most likely they won't. Can't hurt to try.
 
"Wheel runout was just fine. As of right now, I still have one tire that is way off balance. "

Total runout of the mounted tire and wheel combination should not be more than .030 in.. With a little creativity, you can check this in your own garage with very crude tools. Just jack up the car, and slowly move a stable block of some sort against the tread as you spin the wheel. The point where the spinning tire first starts to contact the block will be the high point of the wheel and tire combination. Next, rotate the wheel to find maximum clearance and measure the gap with a feeler gage. The number you get will be total runout.
 
MERCDADDY said:
That would work if your next set of replacement tires came with a high point mark, but most likely they won't. Can't hurt to try.
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New tires (at least the ones I've bought) have the dot on them.

Think I'm going to borrow an "m" stamp from the machine shop, at work, and stamp my wheels across from the dot on my tires before the dots wear off.
 
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