I am sure this question has been asked here before but I am not haveing any luck finding an answer.
I own an '08 F-150 XLT Super Crew 4X4 with stock factory installed 255/70/17 tires. It is time to get new tires and I want something that will make this truck look like a truck. I like the Cooper STT but I want something bigger than stock. I do not plan on installing any lift and was wondering what is the biggest tire I can fit without rubbing on anything.
Can I fit a 285/75/17 ? I have stock factory rims which I plan on using with new tires.
After the tire upgrade what needs to be done to get the speedometer back to correct?

Thanks for any help I can get.

 

Yes that tire will most likely fit. There might be some minor rubbing but nothing you should have to worry about.

You shouldn't have to do anything to speedo. The most the tire will throw it off is 2MPH and that is considered correct by many standards.

 

Don't know how you figure on a 2mph error. The original tires are 31 inches in dia while the 285x75 tires are 34 inches in dia. Thats 10% larger dia meaning a 10% error on the speedo. Thats 6 mph at 60 mph.

 

Tire Size Calculator - tire & wheel plus sizing
This site says that it will be a 5mph difference.
Can the factory computer be corrected for this change? or do I have to get a tuner to do it?

 

If you have a gps device you can run the vehicle and compare the GPS speed vs the speedometer and make your corrections as needed. Just a thought.

 

I do have a GPS, however I was wanting to do this tire size right and make sure I can get the speedo-meter to work correctly.
Can it be corrected?

 

Yes it can be corrected. Some dealers will do it, some won't. Just depends on how friendly they want to be.

A handheld tuner, like Edge or SCT X3 will also allow you to adjust for tire size. In my mind though, the correction is more beneficial for the trans than the speedo. But it can be done.

Look into a tuner, with custom tunes, it's very much worth the money.

 

x2 with mcdavis

the trans will be much happier after reprogramming for the bigger rubber. at least my trans liked it much better.

 

x's 3 Mcdavis / danorules.... trans shifts much better after adjusting for the new tire upgrade.