gullydog

how many inches will 285 tire add to a truck from the stock ones in height
need to know because it might not fit in my garage any more???

chuckr72

285 is the width, not the height, but with that being said, my tires are 325/60/18 which measure about 33" tall. hope this helps

Rambunctious1

If the 285 you are referring to is a 285/70R17, then it is ~33". If you are comparing it to a stock tire which is ~31.5" or so then your truck is now approx. .75" higher than stock (half of 1.5" is .75"). Each tire is slightly different even though the advertised size may be the same as a different brand of tire. Meaning a 285 from one tire company may not be the exact diameter of a 285 from another. Anywho, yer looking at about 1.5" of difference between the stocker and a 285, so figure it now sits .75" higher.

nwjetboat

This might help you out. I use this site quite frequently researching tire sizes..

http://www.miata.net/garage/tirecalc.html

D.Wiggs

The tire manufacturer website should give you an exact overall diameter. Like Rambunctious said, you subtract the stocker's height from the new tire height and then divide by two and that will give you the MAXIMUM height your truck will EVER gain in a "perfect world". However, when you think about it, there are two other very important factors: the tires themselves and air pressure.

If the stock tires have more flex than the new ones or vice versa, one tire might compress more and therefore lower your truck. Also, the same goes for air pressure. If you ran your stockers maxed out but keep the 285s much lower, you might not go up at all because of the new flex in the 285s. It is such an 'individual' thing that the only real way to do it is to max out yur tire pressures and see how much height clearance you have. If you can still spare abouth 3/4", you will be just fine.

powerchokeater

Here is a formula that will get you pretty close.
Example: 285-70-17

The width is 285MM. To convert to standard take 285X.03937 which is approximately 11.22 inches.

The 70 is the percentage of the tread width that the side wall height is.
so you take 11.22X.70 which is approximately 7.85 side wall height. Take this number times two which is approximately 15.70.

Naturally the 17 is the rim diameter. So you simply add the 15.70" to your 17"
rim diameter to get a number of approximately 32.70.

So if you run a 285-70-18 then the number of course would be 33.70"

I have found this number to be quite accurate in all the tires I have checked.

Hope this helps!

D.Wiggs

It's a lot easier to divide when you are finished.

Do 285 x .70 x 2 (for the top and bottom of the tire) and then divide by 25.4 (number of millimeters in an inch). You then add the rim size (17) and there you have it.

32.71 inches. It is the most precise way.