I have a 94 Tercel,
I don't know much about rims or tires but various people told me the highest I could go was 17'' on the rims with 205/40/17 tires so thats kinda how it played out but as soon as I hit a moderate bump, I shredded my rear right tire with the fender well.

Cost me a new tire and while I was at it, had new rear springs-n-things installed, hammered in that right rear fender well, put in some of those crappy coil spring boosters and called it a day. And I haven't had a problem since. Except for those hard U-turns.
I'd give the whole wheel upgrade an 8 outa 10.
Pros: 17's...what more can I say? I get plenty of compliments.
Alloy rims are way easier to maintain than chrome.
17'' Alloy Roms + 205/40/17 tires = less than $700USD
Only grandma hugs tighter than my tires, I live in Chicago and if you've
seen Batman Returns, you've seen the tight turns of Lower Wacker Drive.
(also featured in Crusin' USA the arcade driving game; as an expert course)
and I can take those turns doing 45-55. ON PAR WITH THE FRIGGIN BATMOBILE!
Those wider tires really help out.
Cons: It took a lot of work just to be able to have 17's on the car,
If I could take it all back I wouldn't, but it would be a close decision.
My rims are multi-piece so that little chrome center cap requires detail
not to mention having to read EVERY wheel cleaner product label to see
whether or not they eat your finish.
Final thoughts: If you got the money and you love your car, why not do it.
Unless you want to do an engine swap first. Some people care
about looks while others care about performance. I'm trying to
do both at the same time on a super tight budget. I'm 29 years old
and I'm a father to SIX children, yes 6 kids and I have a nephew whom
I also live with so I treat him as my own also. With that said, I'm grateful
just to have a computer, with internet to be able to post! Let alone own
the beautiful machine I have.