Haven't heard of anyone having issues running 285s with it. For me it has not affected the ride. I'm sure others will say the same. There are many members running the spidertrax.
You should post this in the 4th Gen section, hotrod--you'll probably get a lot more input there, as I'm pretty sure that's a common set-up. Just an idea...
Just keep in mind that the wider the spacer, the more stress on the front end bearings over time. Wider rims will compound it. As far as safety, just make sure the lug nuts on the spacers are kept tight.