my van has 14" rims. i want to upgrade to factory 16" wheels, so i know they will fit, but is there a way to let the speedomete know the wheel/tire size has changed? i know i can fiddle with tire size to keep the same outer diameter so the van wont know the difference, but i think i would like the slightly bigger tires as well. because i am switching from factory base model to factory higher model parts, shouldnt there be some sort of internal setting available to me?

my van has 14" rims. i want to upgrade to factory 16" wheels, so i know they will fit, but is there a way to let the speedomete know the wheel/tire size has changed?

i know i can fiddle with tire size to keep the same outer diameter so the van wont know the difference, but i think i would like the slightly bigger tires as well.

because i am switching from factory base model to factory higher model parts, shouldnt there be some sort of internal setting available to me?

[post="56847"]<{POST_SNAPBACK}>[/post]

Driver, you have stated some conflicting parameters. What do you mean by "bigger" tires? Wider? Different profile?

If you understand tire measurement characteristics, a very good tool that you can use is: http://www.miata.net/garage/tirecalc.html
In order to use this comparison chart however, you must have JAVA on your computer.

You have not indicated what van you are doing this swap on. Early ones, that had
gear-driven speedos, you can change the gears at the transmission to correct
for the new conditions. Later ones, with electronic pulse-driven speedos need a
computer change, that most dealer service depts. can do, if the new size is one that was factory-offered.

Lastly there are after-market converter boxes that are available for some of the
wild, off-road sizes.They usually plug in at the trans cable and act as an
intermediate step to correct the info going to the dash.

If you understand the concept of "plus one" or plus two" tire size changes, the
Miata table is the best bet.
LOL !!! :P

In trucks, they make performance programers that increase the horsepower and torque of the truck, but also feature tire size calibrater where you imput your tire size and it adjusts you speedometer. I don't know if they make thiese for your van tho. I would go chaeck at a REALIEBLE Auto store

Here's another good tire calculator. It recommends staying within 3% of stock tire height. A taller tire puts more stress on brakes and suspension. You'd also get slower acceleration.

I can't really say anymore than what has already been said. What I'd do is look at the overall height of your current wheel/tire combo. Then the overall height of the one you're going to. If they're within about a 1/2" of each other you're fine. Also, just because the van you have also offered a 16" wheel/tire combo doesn't mean it'll be a direct swap sometimes. The wheel hub assembly could be different from one to another.