I have about 40 more HP and about the same # and weight - and I have street tires that are the Hankook Rs212 and track tires the Toyo RA1's.
225/45/16 front on 8" and 245/45/16 rears on 9"
Try
tires-easy.com - the home of low tire prices for cars, 4x4's and vans
I know quite a few people who have been unhappy with sidewall flexing on the ES100's -
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"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough horsepower"
-Mark Donohue