Why does everyone get 520x84 from fancy plates?

[Austin-182]

Looking at getting a small plate and just wondering why everyone seems to get 520x84mm?
I know the recess is 90mm
I dont want to completely fill the recess with a 520x90mm so thought about getting 86/88mm as 84mm leaves a noticeable gap judging the pics ive seen on here

 

[Neat]

I think those that get 84mm want an even sized gap all round. I went for 94mm high which fills the recess vertically and just leaves a gap at each end - exactly what I wanted. If you can be bothered just make a template from cardboard and see what you prefer.

 

[TimR26]

It's because the guide says 84mm.

Here's my 90mm plate

 

[Harpham]

As Neat says, it leaves a nice equal gap all round the plate, rather than totally filling the recess.
Looks better that way imo.

 

[Austin-182]

Cheers lads, yea i agree i think it looks better with a gap, was just unsure as to why everyone went for exactly 84mm lol, like you say the guide is probably the reason why

 

[d19wood]

I went for 520 x 90 after reading the 520 x 84 post. I measured up and didn't see the point ordering the 84 and I'm very glad I did. Not sure about the electrical tape look though, guess it's a bondage thing with the ring