I have a 98 Dakota, 2 wheel drive, 3.9, I currently have 255-70-15s all around, they are getting slim on tread...I have a new pair of 275-60-15's (brand new, from a project car) which I was thinking about using up front and running 31x10.5-15's in the back...thoughts? I have the Dakota Sport rims, truck has 3:55 rear so I am afraid the 275's in the back will make it tach up at 70 or 80 MPH...Thanks in advance....

How about 285-70-15's in the back???? Front tire diameter will be 28.25" and back diameter will be 30.00", it will give me higher gear ratio since the 3:55 kind of scream doing 80...thanks!

 

adding rake like that to a car makes the rear suspension a little unstable because it shifts the balance more towards the front of the car then it already is. the advantage is that the cars front end wont lift under acceleration. since your driving a truck, your rear end is already light and your not going to lift your front end running the quarter mile. theres nothing but disadvantages..

 

i totally agree with kurbycar32 ,and your statement with it taching real high is off it will infact tach low and it will also throw off your speedo too by as much as 8 to 10 mph slow due to the size difference of the tires