I have an 96 LT4. The current tires on it are 255/45-17 (17X8.5 rim) on the front and 285/40-17 (17X9.5 rim) on the rear. I was thinking about geting some Kumho ECSTA tires, but they don't make the 285/40-17. What would be the downside of going down to a 275/40-17 (down from the 285's) & keeping the 255's up front? I eventually would like to go to 275's on all four corners, but don't have the money for new rims for the fronts now.

You can do it if you must , but the bigger the better, I would think an LT4 would have a traction problem even with the 285's.....
I've run all the combo's and 285/315 is the best.......ZR1's run 285/315.......you could try 275/285............but I found the road ruts are still a problem with this setup....going to 275 all four corner's gives you the "rotation" advantage.... http://www.corvetteforum.cc/ubb/smile.gif

Don't worry about it. I've run both 275 and 285 and the difference is negligible.

Okay, correct me if I'm wrong, but I thought ZR-1's ran 275's up front???

I did the EXACT same thing you are talking about PolarLT4, except I have an LT1. I'm very happy with my decision. The Kumho 275's look really good. I love how they don't stick out from the rim at all. I love the tires too. Mathematically your diameter is going to be a little bit smaller so your wheels are going to have to spin a little bit faster. It equals out to a few MPH on the speedo when you're going about 85. Not a big difference.

You are correct ZR1's come with 275 front and 315 rear.

The difference between the two sizes is 10 millimeters, that's less than 1/2 inch.(from sidewall to sidewall) I don't think the difference in the tread would be too much, at least not enough to make a difference.