Many years (decades) ago, when I was in college, I was the proud owner of a 1957 Pontiac. I replaced the original-size tires (whatever they were) with bigger ones and thought I was hot stuff. No one told me that this would make the speedometer read low. The speeding ticket cost me more than the tires did.
Perhaps your pickup didn't get quite so gutless as you thought it did. Maybe the speedometer was just reading low.
If you change to a lower rear end, you may need to do something to the speedometer too; and maybe not, since many modern vehicles read the actual tire RPM for vehicle speed.
__________________
-- Carl
|