The Kirtley kit came with wheels (00 obviously) I think they might be Romford. The above picture shows a comparison with a scale wheel (Gibson) and highlights a problem with 00 gauge steam loco’s While the diameter of the wheels match the oversized flanges mean that the splashers need to be much bigger to accommodate them. They are generally too wide too and sometimes in the wrong place. Some manufactures of RTR loco’s solve this by fitting smaller wheels.
On the left the original splasher (and somewhat crude spring) and on the right my resized version/ I chain drilled a line of 1mm holes inside of the splasher (from the back) and added a new top from some scrap etch.
The oversized splashers mean the boiler is compromised to fit around it. I modified it with some scrap whitemetal disks (from a southern Pride 310 kit – see, never throw stuff away!) Below is the loco so far with new splashers, springs and beading along the footplate. I’ve also mounted the chassis a tad higher into the body since the first image the other day. 
Oversize wheels are just as much an issue in EM as in 00 – even in P4 scaling down clearances can mean things are very tight. The best way to over come this is to scale wheels so they are correct when measured over the flange. This means that nothing should be clashing and wheels are perfectly within service limits without being under sized.