Wheel and tyre size question

[85genius]

I did try searching but there were over 1000 results for tyre size and going through the first 10 pages none seemed to answer my question so thought someone may have a definitive answer.

I was looking at my brothers 1 series and I noticed he also has 17" alloys, (same size as mine but a completely different style) but he has different tyre sizes front and back. His rears are 225 45 17 same as mine but he has 205 50 17 on his fronts so I have a couple of questions.

Should mine have different sizes front and rear like his, I noticed a few people posting similar on the forum but no definitive answer for the wheels I have.

Also are there specific front and rear wheels, so is it possible my car has the front wheels fitted on the back and if this is the case how would I check?

this is the type of wheel I have (not my photo)

 

[mr wilks]

The 1 series will probably have staggered widths & going off your sizes they'd be around 7.5 fronts/8 rears
Your alloys are a "square" set up so will run the same size tyres back & front .
If you wanted though you could fit wider tyres to the rear similar to your brother's without much affect on the speedo

 

[85genius]

Thanks for the reply, to be honest I'm happy with how it handles but was worried it was set up incorrectly, and also thought that with an extra 5mm ground clearance at the front it would be less likely to scrape. If its right for these wheels I'm not going to mess with it