Best way to spike a large tower ( 100 lbs +)

Not trying to be a wise arse but damn the carpet. You found the sweet spot where they need to be? Painters tape around the speaker base on the carpet for a reference, throw 2x4 up under the speakers and install the spikes, remove the 2x4. Now to tweak the exact location you want, wobble them back and forth until you’re satisfied.

The well heeled audiophile will of course invest in this
http://parts.wilsonaudio.com/wilson-audio-flat-jack/

But I’ve never found any problem with the tilt on each corner approach, unless you have very spindly spikes there shouldn’t be any issues

i have much more difficulty adjusting the feet under heavy power amps on stands as these cannot be tilted like tall speakers, that’s when I did need to resort to a set of jacks/blocks to lift the, up

Spikes? Yikes!!!

If you are on a suspended floor, I.e., anything but concrete, do not spike them. 

Spike or not to spike. Seems like one of those issues for which the conventional wisdom will always be a moving target.

My speakers weigh 130 pounds each. I have them spiked on a carpeted suspended floor. I can't hear _any_ difference between spiked and not spiked.

But they are tall and seem more stable on spikes so I leave them in (as recommended by the manufacturer).

Mine came (used) without spikes. Spikes from Aerial Acoustics are silly overpriced in my tightwad opinion. So I made my own from grade 8 bolts.

To move the speakers I walk them spike to spike. No way that is going to stress my spikes. Its heck on the carpet though.

Hurt my back....bad....trying to lift these speakers while kneeling on the floor. It is less about the weight than weight+height. If I need to move them again will put the spikes on furniture sliders.

I have used the tape method but only put the tape (on the floor) around whatever feet I’m using to find the "exact" position I want them in. With spikes this works fine since you can position the spike into the center of the tape outline.

You've not revealed what speakers.  Instead of spikes I would look at the Isoacoustics Gaia II.  They greatly improve performance and you can GENTLY with help move them.  Once in place you might consider the carpet spikes for the Gaia footers as they greatly improve performance on carpet.
http://www.isoacoustics.com/products/gaia-series/gaia-ii/

 I really appreciate the input. I am hoping to give this a shot over the weekend. Markalarsen, I am on a suspended floor, could you elaborate as to why you feel spiking is not ideal? Speaks are Focal Electra 1038be. Thanks again everyone.

That speaker jack from Wilson is just an overpriced version of this:
https://www.calcarcover.com/product/low-profile-billet-aluminum-jack/705

Still better is to have another person hold the speaker while you insert and level the spike. As the old saying goes:
Many hands make light work.
B

I have Vandersteen 5A's....they are spiked on a Travertine tile/cement floors.   Tried those easy slide footers....ruined the sound....a very large step backward.

I would only use the sliders to position the speaker.

Every spike I have is adjustable so there is no need to shim. Try Herbie’s cones. Big plus for me.

I have found Sound Anchors ConeCoasters work great and I could even push my 600 lb Wilson Maxx on my travertine floor.
https://www.thecableco.com/conecoaster-single.html