Hi John , there was a Moparts tire post about a month ago , I hope someone can find it and bump it back up . I think post was named 255-70-15 tires ? Anyway , the moparts members like the 255-70-15 on the back of E Bodys and B Bodys . I just installed a pair of 255 - 70 -15 cooper cobras and I love them . Didn't hook up a Tach yet , but engine sounds like it's spinning 500 or 750 RPM , LESS easy ! I love it on the highway and just drove to the Lebanon Valley Mopar show which is Over 2 or 2 1/2 HOURS on the highway going 70 MPH for me depending on traffic . Cheapest and BEST $300 bucks Ive spent on that car . WAY cheaper than changing a 8.75 dropout , or going to a 5 speed . ronnie