This may sound like a silly question, but is it normal for steering to be affected by fatter tires? I have the sport, with 18" tires.

When driving over bumps and uneven surfaces, the car would sometimes jar or lean in another direction, requiring major correction on my part. I know this is expected of course, but it is very pronounced, more so than anything I've experienced in other cars. The roads around my area are pretty bad, so that may be the reason, but it just feels wrong somehow. On smooth surfaces, it rides straight so its not an alignment problem or anything (I don't think). I guess with thinner tires, I was able to just fly over the little bumps on the road with less of an impact on steering, but with fatter tires it follows the contours of the road/bumps more?? <-- is that logic correct?

Just wanted to know if this is normal... and if its something I need to get used to.

yes, it is normal. It is called Bump-steer and can usually be helped with stiffer bushings and such. I am not too familiar with the G front suspension, but my cobra had 275's up front and it would pull all the time over roads like that. I almost ended up in a wall at one point.
So your logic is correct. Also fatter tires have a greater risk of hydro-planing as well due to the ski effect they have on a puddle. A good tire for wet conditions is key with a wider tire. Skinny tires can cut through puddles easier.
Anyways look into fixes for that with bushings or some other parts that they offer for G's.

check your tire pressures, if they are too high you will experiance that too.

Hmmm...not experiencing this. Are these potholes/cracks etc.? Or ruts that are catching the sidewalls of your tires (that would do it)?

Thanks for the info, good to know. I'll check tire pressures and also look into fixes with the front suspension.

The problem is not due to ruts in the road, since I experience this too frequently to be explained by ruts. I guess I just need to get accustomed to driving with tires fatter than my previous car.

Sounds like your car is displaying tracking characteristics. And you're probably feeling it and are more sensitive to it due to the fact that your previous vehicle did not do that.
As Cobra mentioned previously, it is normal. Because you have wider tires- performance, grippier tires at that- compared to say...a corolla or civic, your tires are giving you a lot more grip and feedback from the road surface, including any ruts, uneven pavement or cracks.
No way to avoid this, really, except to drive with the good 'ol race car driver 3 o'clock/9 o'clock grip on the steering wheel. Its easy to forget that you're driving a high performance sedan with tires and suspension to match.

Happy driving!

It happens to mine too so I guess it's normal .... it's pita when the road condition is bad though....

I have a Z06 with 275's on the front and it does wander on some uneven surfaces and ruts. It's the nature of the beast.
It also depends on how the suspension is setup. An agressive setup thats more neutral will tend to wander more but perform better on a road course.

It also helps if you have wider tires on the rear then in the front. Otherwise like everyone said it's pretty normal.

Hold the wheel gently and enjoy what it is telling you!

one thing you can do to is slightly dial in more toe. this will help the car to track straighter, but you will get more tire wear.

You really need to check the tire pressure. When I had my Volks and new
tires installed they wanted to put 40 lbs in my tires and I let them. That
lasted two miles until I could get it home and let 3 lbs out. It's just amazing
how 3 lbs will effect your ride!