^^ That's pretty much it in a nutshell - at it's simplest, if there's
only a yellow dot on the new tire, then you align it with the valve stem; but if there's a red dot (by itself or in addition to a yellow dot) then it should take precedence over the yellow and you should align
it with the valve stem or marked run-out point on the rim instead.

hyea:
Yellow dots (usually, but not invariably) highlight any weight variation in the construction of a new tire; Red dots (also usually, but not invariably) highlight any Radial Force Variation inherent to the new tires' construction, or if you prefer (altho not necessarily at
its simplest) they highlight any 'out of round' forces in the rolling tire that will likely generate vertical ride disturbances...

And of course, you also need to remember that some tire manufacturers are contrary barstewards who sometimes do things differently just cos they can, so all this discussion hasta be subject to the 'generally usual but not necessarily always invariably' caveat! :shocked: Still, good quality tires made by a well known quality tire manufacturer are usually well worth the extra dollars you pay for them over cheap tires from an unknown bargain basement/knock-off manufacturer; and a trained & skilled tire technician doing their job properly can be worth their weight in tire balancing weights! :thumbup:
Regardless, if you aren't a trained tire technician with access to (high tech) balancing gear and you're mounting a 'quality brand' of new tire that's only got a yellow dot on it, then you should align the yellow dot with the valve stem; but if there's a red dot, it takes precedence and you should align the red dot with the valve stem or the marked run-out point on the rim. If there's NO dot & it's not a 'bargain basement or knock-off brand' of tire, it's usually so close to evenly balanced and round that it doesn't matter how
you mount it, just so long as the rim is also balanced, round, and you mount the tire correctly and evenly onto it! (Altho a trained & skilled tire tech might do it differently!) And seriously, with a good quality tire, a little time, and a few basic tools, it's a whole lot easier than most would think to properly mount a tire onto a rim well enough for most purposes, and most good quality tires available these days usually require little if any extra balancing, especially if it's going on the rear of a Spyder! :2thumbs: