agree 200%!!
dampenining and spring rates always stiffen up over standard/oem therefore on hard brake the suspension system can't compress and absorb as much inertial force therefore causing tyres to lockup sooner... this is evident on those $20 ebay coilover sleeves (which i had).. the ones i bought were rated at 16Kg/cm^2
and on top off that if you get coilovers, most people do it to dump the car and don't correct the camber... already there you've lost half your tyres in traction area.
not many people take this into consideration....