If you go too big, the tires roll on the sides and you do not get as much contact patch. Also you increase rolling resistance with a wider tire. If it were me I would go with a 9 inch slick and get it in a taller tire like a 28" tall tire.
26.0/8.5-15 or 28.0/9.0-15
http://www.mickeythompsontires.com/d...ag_etdrag.html
I use these tires and launch at 6500 rpm's and no tire spin.
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James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft