because with rubber tires/ caps = the tan lotion put oils back into the tire. the certain oils that the lotion contains is comparable to the natural oils that rubber tires have = grip.
over time rubber tire will naturally loose the oils = grip. so adding oils that the tan lotion has is one way to get the oils back into the tire = grip /speed.
my knowledge comes short on foam tire but my theory is that the foam tire do not have the oil content that rubber tires have. jmo a foam tire works from "friction" on the carpet principals more then a "grip" factor. to use tan lotion on pinks /etc. should produce better results then using it on whites, etc because there is more of rubber in the pink over the whites.
but jmo, adding oils into a foam tire for carpet racing is not as important as getting the oils into a rubber tire for asphalt etc.
and simple green is not anything close to a tire prep. Sg has a chemical that will open the pores of a rubber tire wile cleanings out the pours. When used wrong you are hurting your tires with SG, along with getting the dirt out of the pours your also taking the oils = grip out of the tire as well. SG is a cleaner , not a prep. After cleaning your rubber tire with SG you need to add the oils back into the tire = prep. Just an FYI.
jmo: take it for what it's worth.
my knowledge comes from prepping kart dirt tires = back to back track championships and car tires for legal street drags.