Try America's Tire Company or Tire Rack. Tire Rack is cheaper but you have to order than, take it to a place to get it mounted.

I bought mine from America's Tire Company. Some times they match prices along with next day shipping price.

 

Seems odd that you're comparing a summer tire (Kumho MX) against an All-Season (P-Zero Nero M&S). And even stranger that the P-Zero had worse wet traction given that it's an all-season. I'm not saying your experience in the two tires was incorrect, but it doesn't match up with the review ratings on TireRack:

(Kumho MX on left, Pirelli P-Zero M&S on right)
HANDLING RATING 8.60 8.80
DRY TRACTION 8.9 9.1
WET TRACTION 7.6 8.8
SNOW TRACTION N/A 7.5
RIDE COMFORT 7.7 8.8
NOISE COMFORT 7.3 8.8
WEAR 7.1 8.8

I'm not saying the review ratings on TireRack are completely accurate, but 318 reviews on the P-Zero M&S and 375 reviews on the Kumho MX does mean something. The Kumho ASX is a better direct comparison to the Nero M&S if you're looking for an all-season. There's a good comparison here http://www.tirerack.com/tires/tests/kumho_ecsta_asx.jsp

 

Discount Tire or Tire Rack. I like Discount Tire because of the in store service. Great people to buy from.

 

I had asked how the PZero Nero M+S compares to the OEM RE040s. Although it is an all-season tire, it is probably best in class..while the OEM RE040s are probably worst in class. I was interested in seeing how the grip compared b/w these two. The PZero Nero is almost too good to be true according to the tire rack survey - superb performance in every category. I'd be willing to give up just a little grip compared to the RE040s...but if it's a huge difference..i'll probably have to spring for pilot sports.


NzZ

 

I ordered P-Zero Nero M&S mainly due to the the supposed performance and also because of the price. It was on national backorder, but Tirerack is supposed to be getting some (for 245/40/18) early Dec. So I should have mine by mid Dec. I have a G35c and currently have the stock Pilot Sports which are great tires for grip, but a bit on the expensive side to replace. Once I get mine (to go with my new Nismo rims), I'll post regarding percieved grip and noise (which has been getting a bit annoying). I can say that recently I was racing up a hill with a 350Z behind me and it was lightly raining which made the road slipperly. My back end slipped a few times so I back off on the acceleration. Was quite a scary experience.