The wife and I took a trip thru Yellowstone Park over the weekend and ended up spending the night in Cooke City.Anyway I went out about 10PM to have a (ahem) nicotine break,and across the street rootin' around in the back of an older F250 is a medium sized grizzly bear.(yup-I know the difference between a griz and a black-definately a griz)He grabbed a garbage bag and took off behind the hotel.I went and got the wife and we firmly ensconced ourselves in our 08,knowing he'd be back for more of the garbage al a carte.He came back of course,and we got to watch him make a royal mess for over an hour.We felt absolutely safe in our SD cuz we had no pickanick baskets or honey onboard(Are ya sure the windows'll roll up when ya hit the button thingy??? Yea hun they go up REAL fast....Are ya sure????Yes dear...)He didn't care about us cuz of the smorgasbord of ripe refuse.Well he ate all the tasty stuff and then just sauntered down main street and off into the night.The pics are pretty dark but the wife is tryin' to clean em up on photoshop.Short disclaimer kids...maybe ya shouldn't try this at home.I'd hate to be responsible for chewed on Ford Enthusiasts.....To make this more relevant to our forum--I just switched the stock tires out to 35/12.50's and figured this would really screw with the computer,ya know throw the avg mpg meter waay off.That's a 2" height gain.I haven't gotten the speedo recalibrated yet and wonder if it's even worth doing-it's got a standard tranny so shift points aren't an issue.Anything else it can mess with?Thanks

 

A change in tire size can also throw off your ABS system.

Just using what you threw out there, going from ~33" tire to a ~35" tire would introduce roughly 6% error into all of the calculations done by the computers.

A speedometer indicated 10 MPH would really be 10.6 MPH.
A speedometer indicated 30 MPH would really be 31.8 MPH.
A speedometer indicated 60 MPH would really be 63.6 MPH.
A speedometer indicated 75 MPH would really be 79.5 MPH.

It is my understanding that the computer will not accept a tire revolution per mile value less than 600. Unfortunately, anything above about 34" in height falls beyond this line. As such, if you do want to correct it you will probably have to resort to something like Superlift's TruSpeed. (Do a web search....plenty of places to check one out.)




Being from WY, the bear problem in Yellowstone is kind of sad. It is simply amazing, to me, that people don't take the appropriate steps while within/directly around Yellowstone.

 

Too bad you didn't get to see the bear maul the people that left the garbage out.

 

Being an 08 you should take it to the dealer and let him recalibrate it for you because it will also throw off your odometer / tripmeter. It only takes a few minutes for them to do and is fairly cheap.

 

On the bear thing-although it's really neat to see one,the shame of it is this one's fate is probably sealed-relocation at the least-a bullet if it's deemed a "problem" bear.
On the truck thing-I thought it would make a way bigger difference.On my 01 it really screwed things up.(Whacking forehead with hand)prolly cuz the 01 had smaller diameter tires stock, huh?Duh.On our Jellystone trip I was amazed that the avg mpg just kept going up.The Park just isn't the place you think you'd get good mileage with all the critter jams,hills,stop and go,ect.,even tho the speeds are lower.I never went fast enuf to get into OD.At the beginning of the trip the avg mpg read 12.2-it was up to 12.6 when we got home.I have not reset the mpg meter since I got the truck, and I got a little over 2100 miles on it now.I figured I got 13.84 mpg inside the Park.And with the speedo bein' off it should even be a little better than that.I was pretty happy with that.But guess I should call the dealer and see about the recalibration just to be on the safe side if it can effect the ABS.