Some tire guy told me that the set up 205/55/16 front, 245/45/16 rear is a wrong set up for s2k because the front tire is taller than the rear and will mess up the "abs system".
Not sure if that's true, and don't know what an "abs system" is...
205/55/16 = 24.8779" overall wheel diameter
245/45/16 = 24.6811" overall wheel diameter

Any opinions on this?

 

Let's see... If the goal is to have front and rear tire diameters the same (assuming same rim size):

245 * .45 = 110.25mm sidewall height

If you want a 205mm width for a front,

110.25 / 205 ~= 0.54

So you'd want a 205/54/16 front tire. I don't think they make it in that size, so 205/55/16 should be ok.

I think the real problem is your tire guy misunderstanding the sidewall height to be actual length, instead of percentage to the tire width.

 

Sorry, I just realized that you already did the correct math. You're really asking if it's ok for the front tire to be larger than the rear.

Well the stock tires are:
Front: 205/55-16 = 112.75mm
Rear: 225/50-16 = 112.5mm

So the oem front tire is already taller than the rear. ABS is Antilock Brake System.

 

OH Stupid me!!! ABS system!! I was thinking what the hell is an "Ab" 's system?...
No more Ab's work out for me.

Well, looks like the tire guy doesn't know as much as our s2ki members do.
Shouldn't doubt myself.

thanks.

 

Your "tire guy" is a flat out idiot. Plain and simple. Sorry to be so blunt (my MO so to speak but I'll cheerfully plead guilty). Tell him to do some research on how ABS works and spend a decade or two running with assorted configurations on ABS-equipped vehicles and then perhaps he'll find time in between teachings to apologize to your for his misguided ignorance. A quick example. My front tire is a 24.3-inch Kumho while the rear is a 25.1-inch tire. No problems whatsoever. Another point that I am flabbergasted he neglected to mention. One manufacturer's 205/55/16 may be constructed differently than another and as a result can actually deviate in height by as much as .25 of an inch even though both tires in the comparison are sized exactly the same. The WIDTH of the S0-2 is such an example which should clue this goober in that height is also going to be affected. I've seen photos of tires sized identical and you'd swear there must of been a labeling mistake, the difference was that noticeable.
This kind of advice coming from someone who works at a tire place is pathetic.