Changing rims/size

[cupnoodle]

Hi all,

Just a quick and easy one. I was wondering if changing rims or size of the rims affects the vehicles performance or handling in anyway whatsoever?

Furthermore, would the ECU/speedo take into account the change in wheel circumference and reflect an accurate speed?

Much appreciated

[Red_EG4]

The change in rim size will affect handling performance. I don't know the technical specifics so I'll leave that up to the smart guys on here.

The ECU/Speedo will not take into account the change. If you get a lower profile tyre to keep your rolling diameter as close to stock as possible the speedo won't vary too much.

This might help you out a bit;
http://www.carbibles.com/tyre_bible_pg2.html

[markCivicVti]

If getting bigger rims, then get the correct lower profile tyre so that the spedo/odometer isn't out.

Use this to determine the correct profile:
http://www.1010tires.com/tiresizecalculator.asp

The lower the profile of tyre the less cushioned the small cracks and bumps will feel as you're driving. lower profile tyres are better for cornering as there's less flex in the sidewalls (they'd be much stiffer). Lower profile tyres are normally noisier too and cost more.

So when getting rims make sure everything is right including the offset and pcd (who many lug nut holes and how far apart they are). Then make sure ur getting the correct tyres for that spec rim also keeping in mind keeping your overal rolling diameter the same.

Also bear in mind that aftermarket rims need different lug nuts (normally 60 degree tapered) to oem wheels. Even though oem lug nuts may fit and tighten they are not safe a they aren't seated correctly against the rim.


a better tyre calc imo:
http://www.miata.net/garage/tirecalc.html
offset calculator (useful to get an idea of whether to expect scrubbing and just the overal outcome of changing rims:
http://www.1010tires.com/WheelOffsetCalculator.asp