Yes, the guy at the wreckers was right.
Its not so much the tyre size as the offset you need to look at with rims. The offset is how wide the rim itself is, to wide and itll scrub.
You can put varying sizes of tyres on a rim, for example, when I bought my lancer it had 14" rims with a 5.5 offset running 175/65/r14s but I changed that to a 185/65/r14
There are limits to how wide a tyre you can put on a rim but you can go wider.
The 94 mirage and the 94 lancer were almost identical and they kept that going through most of the models. While the mirage turned into a hatch and the lancer into a brick most of the earlier models shared parts.
Hope this helped
p.s the guys at the wreckers generally tend to know what they are talking about :P