Mazda Talk Forums

Since I upgraded my ND stock tires to 215/45 17, the height of the sidewalls raises the car and therefor center of gravity nearly 1/4" or 6mm. The car is not lowered, just RoadsterSport SB.

I guess reading racing and performance driving books has my mind thinking of issues that probably are not really a problem for DD, mountain roads and occasional Autocross (just started).

To offset the added weight transfer during corning, a 3mm spacer should offset the effect; adding 6mm to trackwidth. Given mass and lateral forces as unchanged, the other part of the formula is CG/TW. This is a direct relationship so if you apply the same amount of change to both variables, the resulting ratio does not change.

Questions:

1) Does the increase in tire height of 1/4" really matter and or is noticeable in handling?

2) If yes, then is there any negative impact on using the 3mm spacers like bearing wear or less stud for proper torquing? Using McGard lugnuts.

3) Adding the spacers adds to unsprung weight, is it enough to matter?

4) Any problem with a 215/45 tires with a 3mm spacer hitting the fender or wheel well?

Thanks for any input, advice or suggestion.

Andrew

Hi Andrew

For daily driver the slightly higher CG not going to make any difference, car is not being driven within miles of the limit in daily driving. Our 3mm spacers are aluminum, mere ounces, not enough additional unsprung weight to notice.

Thanks for the response.