QuestionI own a 2006 ford F-150 FWD (no 4x4 ) with a 5.4 run of the mill motor, would like to know if I could install BF Goodrich Rugged Trail T/A LT245/75/R17 tires on it without modifications, lift kits or radious problems. I currently have Michelin 255/65/R17, the T/A'S stand about 2 3/4 inches taller from the Michelin's.
thank you .
Fred
AnswerDear Fred,
Thank you for using AllExperts.
My records show that several 2006 F-150 models were originally equipped with size P255/65R17 tires with a "load index" of '108' requiring 35 psi front and rear. 'LT' (light truck) tires as you are proposing are designed to a completely different formula compared to 'P' (passenger) type tires, therefore if you were to install the LT245/75R17 tires you would have to apply MUCH more air pressure to carry the equivalent load of your P255/65R17 tires. For example:
P255/65R17 max load = 2,205 lbs per tire at 35 psi
To achieve the same load, you would have to apply 49 - 50 psi to the LT245/75R17 10 ply (load range 'E'). This would result in a much harsher ride.
Why do 'LT' type tires require more air pressure than 'P' type tires? They are a more heavy duty type construction, may have additional plies and material which make them run 'hotter' in service, thus requiring more air pressure.
Dimensional difference:
I show the dimensional difference as:
P255/65R17 = 30.31" (traction tread)
LT245/75R17 = 31.73" (traction tread)
The larger overall diameter of the LT245 will adversely affect your odometer, speedometer, and braking efficiency.
DT
