A big factor in limiting how much power can be put down to the track in heads-up racing is the tire design and size. The traditional theory has always been, the smaller the tire, the harder it is to throw power to the track. Veteran racer Brad Medlock has been on a tear this year in the MX235 and 8.5-inch tire racing classes, bringing home numerous wins and defying the concept that tire size matters. Now, he owns the 8.5/235 radial tire record with a blistering 4.615-second run, recorded at the NMRA World Finals.

Medlock’s 1995 Mustang uses a Kuntz and Company 8.2 deck small-block Ford motor with Edelbrock Victor heads. That engine, with an 85 mm Precision turbo has rocketed Medlock into the 4.60s in MX235 trim this year. To compete in the Street Outlaw class at the NMRA World Finals, Medlock had to make some changes to his combination. “Normally we run an 85 mm in MX235, but to set this record we put on a PTE 98 mm and a tighter Pro Torque EV1 converter in the car,” Medlock says.

The splits for the record pass are impressive for such a small tire, with a 1.18 60-foot time and a stout 3.08 to the 330-foot cone on the way to the 4.615 record. “This small tire is great, but still finicky as to how much power you can apply. Therefore, weight distribution, power management, and spring rates are all key to getting down the track. We’ve also tested multiple gear ratios, countless torque converters, and tuning combinations to get us to this point. My crew chief, Barry Phillippi, is a huge part of our success because of his ability to read the track and keep me in the groove,” Medlock explains.

The plan for Medlock and his team going forward for this year is to put the 85 mm turbo back on and try to reset the MX235 record at Holly Springs with a 4.65 pass.