Tire size

[Ppd1979]

Looking for the estimated ground to center of a 275/35/18 tire based on a front end weight of 1800lbs.
Generic diameter shows 25.7", and a radius of 12.85"

[dontlifttoshift]

What else do you need to know. Diameter will vary from brand to brand and will be smaller after burnouts.

You can plan on the tire flattening at the contact patch and that will put spindle centerline .187" to .250" closer to ground. That number is void if you set a bunch of negative camber into it as the inside shoulder carries the load and the tire flattens very little on the outside shoulder.

This is really splitting hairs.....what are trying to do?

[Ppd1979]

Make a bracket to hold the spindle/knuckle at ride height, to set up the suspension for my car.

[dontlifttoshift]

Ok, for that I always just figure tire radius and work off of that.