I put too much load in the rear and white stuff squirts out.

Now that I have your attention...

My rear tire burps a lot, wasting my Stans sealant and forcing me to stop and slap some CO2 in there. I ride XC on a hardtail, but up, down, in a corner--your name it--I put so much load on the rear tire that it always burps. I'm running tubeless with a Crossmax SLR and Maxxis CrossMark tires (non-UST) at 27-30psi.

I could pump it up more, but are there any tricks to prevent burping?

I dont know if these tires just arent good, or if I should just get a fullsuspension if I put so much in the rear.