Figured some of you may be interested in this if you have not seen it already:

For those with portable Apple devices, there is a now little nifty app that may help visualize rim offset related questions.

It has an interactive diagram that shows the new spec rim relative to your existing rim. It even estimates clearances if you measure and enter them in from your current wheel setup.

Here is a screenshot from iTunes site:

 

edit: found 2 called Rim Offset (I think it's the one you're talking about) and Wheel Calculator. I also found one called Tyre Size Pro that seems to be handy. All are 99 cents.

 

Yeah, I think each of these target a different goal with some little overlap between them. From looking at their description, I gather the following:

Rim Offset - concentrates on just working out how much wider or narrower a new rim is on each side relative to original one. It also works out clearance values if you want to play with them and adds spacer calculations into the mix. Best part is that it shows you a nice dynamic diagram that changes with the values as opposed to just giving you a number. Does no speedo error math. Probably the best one to answer "will this wheel fit on my car" or "what spacer do I need" type of questions.

Wheel Calculator - works out the speedo error due to diameter & tire size differences. It also gives a clearance to hub numerical values. No interactive diagram or clearances to strut or fender options. No spacer calculations.

Tyre Size - Just deals with tire tallness and width calculations. No overlap with Rim Offset, overlaps some of the tire math with Wheel Calculator. Seems to do something with offsets as well - gives maybe a difference value on the outer and inner side. Probably the best one to use for "Will this tire fit or rub on my car" or "how will my speedo be affected"

 

cool app. lol

 

hey that's an awesome app!! Very helpful =]

 

Thats pretty cool.

 

Awesome - I'll give it a try in a few.

Got some new wheels in mind