what's the popular CHEAP track tire nowadays?

[i3igpete]

My back two tires are almost completely bald. i'm planning on replacing those two, and finishing the rest of the season with the RT-615's currently on the front before getting rid of those. Back when I originally bought the falkens, they were the super duper cheap option on the market, at $130 apiece. Now they're a bit pricier and fall into the range of other competitive tires.

nitto NT01 $~210 = I hear this R-compound can be used without shaving
nitto NT05 $~160 = Cheapest street/track tire I could find, compound similar to NT01
falken RT-615K $~180 = Commercials claim 1sec lap time improvement from previous gen
bridgestone RE-11 not available in 275-40-17