Q Every so often I see a truck or big semi with bolts on its front wheels that are huge sharpened spikes. They look scary as hell and could do a lot of damage to another vehicle that got too close. Why do they go for these? Is it bling or are they thinking to do a road battle like in a Mad Max movie? Are they thinking to warn cars from cutting them off?

Rebecca Ree

Oakland

A I've often wondered the same thing, but rest easy. Ray-the-Tow-Truck-Guy says these spikes are just harmless lug nut caps:

"They may look sharp and dangerous, but you can bend them with your fingers and they pop right off or crush easily. I have round caps on my truck. They are not much thicker than foil."

Q One of the few pleasures in my commute up Highway 101 is to watch the slow and steady progression of license plate numbers, marking the passage of time. The sequence progresses slowly from 6AA to 6AB to 6AC.

But suddenly, the numbering is out of control! I hardly remember seeing 6X or 6Y or 6Z, but we are already up to 7. And not just 7A. I recently purchased a car and got plates 7DB. My friend bought her car just a few weeks before me, and her plates are 7CA. What is going on?

Chiye Yamamoto

San Jose

A Stay with me on this, for it can get complicated.

License plates are manufactured in numerical sequence, but not necessarily issued in numerical sequence. The DMV currently uses 7-digit configurations that are specific to different types of vehicles. They start with a "7" for autos. Passenger vehicles (sedans, SUVs, convertibles, etc.) are classified as autos and issued two 7-digit plates that follow a pattern of one number, three letters and three numbers (1SAM123).

Two and three-wheeled vehicles such as motorbikes and Vespa-like scooters are classified as motorcycles and given a single, smaller plate with two numbers, a letter, and four numbers (12A3456).

Government vehicles are issued 7-digit plates, and all digits are numbers (1234567).

Plates are manufactured in sequence by the Prison Industry Authority at Folsom State Prison, which produces over 8.5 million plates a year and is the single biggest correctional license plate factory in the U.S. They are then shipped to various locations, such as DMV field offices and auto clubs. Each of those issues the license plates it has on hand, so they do not necessarily come out in sequence.

Q For about 20 years, the lights at Pollard and Quito roads in Saratoga were "smart" in responding to traffic. Now they're "dumb," making motorists wait although no other vehicle is in sight.

Why the change? Is the light sick? Can it be cured?

Eric and Ginger Good

Saratoga

A Sure can. One of the traffic loops for turns has not been detecting cars properly and will be replaced soon.