Help with tire shake.

Car weight is 2550, bore is 4.500, stroke is 4.250, converter stall is 6000. Tried to put a larger tire, but would not fit a 34.5. I understand that it would be better if I could use a larger tire, But there are 10.5 tire guys getting down the track faster than us with less tire. Whats their secret?
obviously,We are not trying to set any kind of records, The motor is an Oddy built motor that dyno'ed at 2345 @ 7500 rpm, so at 2550 lbs we should be able to run 6.70-6.80 range without being on kill.That is if we can get past 100 ft without knocking down the guardrail.