cocteau

let me say right away that i am new to the idea of having to buy snow tires, so i am a touch confused on sizes and what the right tolerance is.

i bought 215/55/16 michelin alpin's. tirerack recommended them. i have seen lots of postings about people buying 205/55/16. i can do the diameter calculations and it seems that the former is 25.3in. the latter is 24.9. is this difference important?

right now, rufus (yes, he is a roadster) has 225/45/17 on, which have a diameter of 25in.

so, am i better off with the 215/55/16 michelin alpin or should i go for the 205/55/16 dunlop? it seems that the michelin's don't come in a 205 size.

sorry to be a pest, but this is a beautiful mystery to me... i would really like to understand where the significant digits are in this calculation (ie are 25.3 and 25 and 24.9 all the same?).

M.

Roger

Your 215-55-16 Michelins are 1.2% oversized which will slow you down slightly. You won't notice it.

They're also wider than the standard 205-55-16s and aren't ideal if they are mounted on the one steel wheel that fits TTs. (That wheel is even too narrow for the 205s.)

Keep your Michelins.

TA-TA

at the cost of mount and balance, the wheels will pay for themselves in 4 seasons. the 205s are too small for regular dry drives, and will still be much better than stock in snow.