I can't comment on the minimum ride height, but I have the 5" lawn edging from Home Depot for a front air dam on my car. It is about 3-4" off the pavement. It rubs all the time. Speed bumps, driveways, etc... I really like it because it is very durable. The snow and ice recently hasn't even cracked it in 20 degree weather. The asphalt has been the most abrasive on it by wearing it away. At $13 a roll, it gives you enough for two front air dams, so it's a great deal. I'd also use it for side skirts...
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