I just bought my first Suzuki, a 2003 Grand Vitara.  I has 235-60-16 sized tires which may be the original tires based upon the manufacture date of 2003.  They look rather wide to me and the rims don't look like stock OEM rims but I am not sure.  The center of the crome rim says "ASA" on it so i am pretty sure they are not stock.  Anyways this little SUV feels pretty squirrelly as I drive down the road.  It wants to over-react to the irregularities of the chewed up California haighways.  The steering feels firm and fine, it just that the car will want to pull hard left or right if it encounters a small ridge in the road.  Is this common?  If not, what should I have checked out?    I attached a pic of the rims if you can figure out how to view it.  Any help would be appreciated.
David

No - those are not standard rims - 235/60R16 is one of two OEM sizes, but may not have been the one fitted to yours - if yours originally had steel rims it probably had 215/65R16s on it.

No it should not feel squirrely, they're normally quite stable - at least mine is - might be tires, suspension or alignment.

If all of your steering componets are tight I would start by checking your alignment.

Zig

As Zukipilot said, check to make sure nothing is loose in the suspension or steering.  Try pumping the tires up to about 35psi and see if that helps. 

35psi is waaaaaaay too hard - 26 psi is the recommended pressure - it shouldn't feel squirrelly at 26 psi.

Not for normal driving, but it will give you an indication as to whether or not the tires may have broken cords.

Could you explain more please.

I have had cases in other vehicles where a combination of uneven and low tire pressures would cause the vehicle to "wander".  Evening out the pressures should tell you if this is the problem.  I recommended high pressure because this takes a lot of the sidewall flex out.  With high and even pressure, if it still pulls, it would most likely indicate a problem with suspension wear or alignment.

Myabe naive of me but, I would have hoped that the OP would have at least checked and if necessary corrected the tire pressures as the first step - and as for that last part ...

With high and even pressure, if it still pulls, it would most likely indicate a problem with suspension wear or alignment.

Two points - first - to me pulling and feeling squirelly are not synonymous, and second - I've got a couple of tires here - with what I think are brokens cords or belts - they're no longer round, so you get the sensation that the car is weaving or wobbling and the higher the pressure, the more out of round they become, so the more pronounced the sensation.

Going back to the OP, specifically described pulling when encountering a ridge in the road, and did not mention checking pressures.  I was just being "Captain Obvious"...  (ie. check the most obvious (and cheapest) possibility first)