California wheel and tire combo weight of 63lbs !

Yup those big wheels are heavy. That's 36 lbs for each front rim. Nothing normal about that if it's a forged quality wheel. A good aftermarket forged monoblock 8"-9"x20" wheel will be between 18 and 20 lbs. depending on rim width and offset - some even less, and a 21" 2-4 lbs heavier. On a rim that large where a lot of the weight is at the barrel and the barrel is also larger than OE, that easily equates to 7-8 lbs. in the car per 1 lb. of unsprung rotational mass on the rim. I believe the front forged Cali rims are 23 lbs. That's 26 lbs. more on the fronts, so that's like 182 - 208 lbs. in the car for the front rims alone.
If we add the difference in tyre weight it will look like this. The OE MPSS K2 245/35R20 is 23 lbs. Your 255/30R21 is 27 lbs. Now most of that weight is in the outermost part of the tyre i.e the tread which is also larger in diameter than OE. So that's probably 8-9 lbs. to the car per 1 lb. So those 8 lbs. for tyres is 64 - 72 lbs.

So for the front it's like adding 246 to 280 lbs. of sprung weight to the car - and that's not even including the rears. If you're running 335/25R22, the effect on the car must be huge as not only is the rim barrel a lot larger than OE, but so is both tyre weight and diameter.

Funny how few wheel manufactures inform their customers of these things.

EDIT:

Here's a quick example of light aftermarket forged wheels that fits the 458 and Cali.

OZ Superforgiata polished version.

Front: 8.5" x 20" ET 44 19.5 lbs.
Rear: 11" x 20" ET 56 21 lbs.

 

I hear you Bill, and here's some information for you. To start with, 3-piece rims look nice but they are generally heavier than monobloc rims.

The old (1975) 308 had 205/70-14 standard tires probably on alloy monbloc 6.5x14" rims which computes to a 87.96" circumference and surface area of 6.5 x 87.96 = 571.74 sq inches. Your Cali's (aftermarket) 255/30-21 wheel has a 3-piece steel/aluminium 9x21 rim which computes to a 131.94" circumference and surface area of 9 x 131.94 = 1,187.5 sq inches.

So you see the surface areas of the 2 barrels themselves already differ by a factor of 2 and we haven't even considered the metal density differences between alloy vs steel barrels. And then we have the different weights of the tires. Have you ever lifted a 255/30-21" tire by itself? There's also the rim centres but we'll just assume they are similar in weight.

Anyway, with these empirical considerations in mind, the weight of your new 255/30-21 wheels would not be surprising.

I had my 245/35-20 and 285/35-20 diamond-cut (cast) Ferrari sport wheels weighed when they had about 8400 km on them and they were 54 and 66 lbs respectively. Big wheels do weigh more and forged rims are lighter than cast ones so the original standard Cali 19" forged wheels probably weigh quite a bit less.