Question about wheel height.....can anyone Knowlegable help ?

[KRATEDISEASE]

I tool off the stock OEM factory wheels that were on my 1997 Viper GTS. I replaced them with the 2009 model year factory 6 spoke wheels with new tires.

What I am wondering is how much higher is my car sitting and how will that affect handling ?

The stock front tires went from 275/40/17 to 275/35/18

and the rear tires went from stock 335/35/17 to 345/30/19


The conversion is already done and I am happy except that the car rides apparently a bit higher.

would anyone know factually (without estimating) what the difference in size of the new tires are to the old ones in overall diameter (total height) ?

I tried to calculate but I am wondering if I am coming up with the correct numbers,

Possibly Nine Ball can better help since he sells/manufactures wheels and I think he is an engineer by profession.....

I calculated from the tire rack formula that the 275/40/17 fronts sidewalls are 4.33 inches high plus the rim at 17 equals total height of 21.33 inches
I calculated the new 275/35/18 front sidewalls would be 3.78 plus the rim height at 18 for a total of 21.78 inches in height

Then assuming the radius is half of the total height then I assume the front of my Viper is around .23 inches higher ???

Is my math correct ??

and for the rears, I got 335/35/17 sidewall as 4.6 inches, plus the rim at 17 for a total wheel height of 21.6 inches
and the new rears at 345/30/19 sidewall calculates at 4 inches plus rim at 19 for a total height of 23 inches.

so in the rear I added about 1.4 inches in total wheel height diameter which would raise the car .70 inches in the rear

Does this seem correct to anyone who is qualified to verify my calculations ?

[Nine Ball]

Total tire height is 2x sidewall height + wheel diameter

Front
275/40-17 (25.6") to 275/35-18 (25.6")

Rear
335/35-17 (26.2") to 345/30-19 (27.2")

Front height difference is negligible. Rear should sit approx 0.5" higher, since the tire is 1" taller. Half of that tire height difference is above the axle line, which is why the vehicle is only 0.5" taller in the rear.

Shouldn't change handling or anything. Suspension geometry hasn't changed. Might even handle better if you upgraded tires.

[KRATEDISEASE]

Total tire height is 2x sidewall height + wheel diameter

Front
275/40-17 (25.6") to 275/35-18 (25.6")

Rear
335/35-17 (26.2") to 345/30-19 (27.2")

Front height difference is negligible. Rear should sit approx 0.5" higher, since the tire is 1" taller. Half of that tire height difference is above the axle line, which is why the vehicle is only 0.5" taller in the rear.

Shouldn't change handling or anything. Suspension geometry hasn't changed. Might even handle better if you upgraded tires.

Thanks Tony.... I was hoping you would answer since I know you are absolutely qualified and are an expert in the subject of wheels and tires.

Thanks again so much.

[Jack B]

Approx 4% speedo error.