Just bought a 2001 F150 reg cab 2WD with P255/R70/16. the tred is not so good. According to Tire Rack I should have 235's not 255's, but the sticker on the truck reveals I should have 255's. What's the difference and should i stay with 255's?

 

The 235's were more than likely the standard tires for that year. If the original window sticker says that the truck came from the factory with 255's, it was probably an option that was installed at the factory. The tire shop is just going by what they perceive as "stock". They don't carry a list of optional tire sizes offered for every year of every make and model vehicle, and every vehicle offers different tire sizes on it's optional equipment list.
Go with what is on the window sticker.
Just for info, my '02 2wd Lariat came from the factory with P275-60 R17 tires.

 

255 was a factory upgrade.
If you get 255 your truck will perform the same as it does now in regards to accelaration, shifting and speedo will remain constant as will the odometer.

 

Sounds like you have the stock 16x7 wheel. 255/70 is/was a stock from the factory size on some F150's. But, you can use

235/70's
245/75's
255/70's
265/75's

and several in between sizes on the stock wheels. A dealer will be able to program the computer to any of these tire sizes so the speedometer will be accurate.

Tire dealers are worried about liabilities of installing the wrong size tire. They don't ask what tire you want, they ask what car you have and look it up. You should be telling THEM what you want, just do your homework.

 

The 255/70/16 tire package was a $295 (retail) option in '99, but Ford threw it in as a freebie on my V6 XLT. When I was shopping, every 4.2 V6 on the lot had a credit for the 255/70 tire package.

Many, many trucks were equipped with this option from the factory.