Ok guys - my 18" Volks will be here next week, so I am doing a final check on anything I may have forgotten. Some questions I have:

Should I get an alignment done as well as the obvious mount and balance?
Do I need to buy a yellow box to correct the speedo/odo or is there an alternative method to doing this (say a visit to the dealer for ECU programming or something)?

I can't really think of much else - the tires are in the garage just waiting to be put on but since this is the first time I've bought aftermarket rims I thought there might be some lessons learned

 

As long as the overall diameter remains the same a speedo correction device (yellow box) isn't needed. As for the alignment, if you currently don't have a problem you are fine. Unless you are lowering the car at the same time.

 

So how do I know if the diameter has changed?

 

Post the tire size that you bought.

 

Use this tool to see how much the diameter will change:
http://www.miata.net/garage/tirecalc.html

 

Also, try and find a quality shop to mount the tires, with wheels larger than 16", if you're not careful, the lip can get scratched during the mounting.

 

Be sure to take the old ones off before you try to mount the new ones.

 

Fronts:

Old: 24.9
New: 25.1

Rears:

Old: 24.9
New: 25.0

Is that close enough or a problem?

Terd: The rims are brand spankin new so they've never had tires mounted on them!!

Any recommendations on where to get them mounted/balanced?

 

On new wheels, it is recommended to retorque the wheels after fifty miles.

 

Don't use stock lugs.