Long gone are the lengthy wheel-base land cruisers of the past. Their highway space has been taken by mid-size cars, compact cars and now mini- and micro-cars.

All of these are smaller than the 1960 Cadillac that could have hauled five NBA starters. After all, it was nearly 19 feet long with a curb weight of 4,722 pounds. My late model 4×4 Blazer only has a curb weight of 3,536 pounds, and my next vehicle won’t be anywhere near that.

Be that as it may, a 1960 Caddy used “high test” gasoline at 30 cents a gallon, put up numbers that were less than 10 mpg and nobody cared. Why would they? Times were good and the U.S. was “the” major global economic superpower.

Today times are not as good, so automakers and tiremakers are on the hunt to relieve household budgets, as well as present an uncomplicated way to get to and from work with reasonable operating costs.

In that spirit, enter the SmartCar – all 8.8 feet of it – with miles per gallon set at 40 or 41, depending who you talk to. The pint-sized two- or four-door car also features different front and rear tire sizes: 155/60R15 on the front and 175/55R15 on the rear. Without the driver, this hummingbird of a car sports a curb weight of 1,653 pounds and the two-door model can handle a payload of just 507 pounds. The wheelbase on this mighty mite is just 73.5 inches – about the length of a very short NBA guard.

This vehicle was first spotted in Europe in 1994, the product of a Daimler Benz and Swatch Watch project. So small is this car that stories abound when it comes to parking the little ride. Here goes: If the car won’t quite maneuver into a parking space, lift it up with your buddies and carry it into the space. Two will fit side-by-side comfortably in a standard American parking space.

Here’s the problem with this car, if there is one: If you and your passenger each weigh 200 pounds, you only have a margin of 107 pounds to haul something. Heck, you can’t even fit a golf bag in the tiny trunk, if that’s what the cargo space can be called. The good news here is that the SmartCar is visually interesting. The bad news: it screams lack of load carrying capacity.

No wonder the SmartCar only requires a three cylinder, 1-liter engine that generates the 71 horsepower needed to push it up to 90 mph.

When it comes to replacement or upgrade tires for the SmartCar, all you have to do is check the maximum weight allowed by the manufacturer and be sure you don’t overload the tires. You’ll find this information in the owner’s manual.

Still, there are a few twists to the SmartCar’s tire and wheel package. Although it is expected to cause no problems, the OE wheels come with a three-bolt pattern. But because of the wheel size differences – 4.5 on the front and 5.5 on the rear – tires cannot be rotated as usual.

You can rotate side-to-side, keeping the fronts on the front and rears on the back, but that’s it. When a customer comes in with strange wear patterns and tread depths that are on the borderline, you have no choice but to tell the customer he or she has to replace all four tires.

You can, of course, rotate side to side, but this is not always advisable given the oddities of tire wear patterns. The owner will most likely come back with ride complaints.

Another surprise from SmartCar makers, operated by Penske Auto Group in North America, is the fact that premium fuel is required. This isn’t particularly good news with the availability of other micro-cars that offer higher mpg on regular unleaded fuel.

Up next is the Toyota Yaris, with a curb weight of 2,295 pounds and a maximum load carrying capacity of 979 pounds. OE tires are P175/65R15 84S all around. Wheel base for the Yaris is 96.9 inches, with an overall length of 150.6 inches, height of 60 inches and width of 66.7 inches. Better yet, this car seats five.

As a reminder, here’s a rule of thumb offered by the Tire Rack when reviewing load carrying capacity. For example, when dealing with a P195/60R15 87S, the 87S is the tire’s service description. The 87 represents the tire’s load index, in this case 1,201 pounds, while the S represents the tire’s speed rating.

Applying this to the Honda Fit, the OE 175/65R15 84S tire’s load carrying capacity is 1,102 pounds, while the optional size for the Honda Fit Sport, the 185/55R16H, will carry 1,074 pounds.

In general, most mini- and micro-car builders consider a passenger and driver weight of 150 pounds each. Another rule of thumb is that the lighter the car, the lighter the payload. That shows you just how little margin for error there really is here.

A look at the 2009 Honda Insight turns up a 175/65R15 84S tire size. In this case, the load carrying capacity of the tire is 1,101 pounds. Meanwhile, the Toyota Prius is fitted with P185/65R15 86S, a load carrying capacity of 1,168 pounds for each of the four tires mounted on four 15×5.5 alloy wheels.

Smaller Service
With the growing popularity of these vehicles, you had better be certain you’re ready to handle, service and warehouse the imminent growth of smaller size tires. It might be a good idea to remind everyone in the store that only the vehicle and tire size has changed, and nothing else (with the noted front/rear tire size exception on the SmartCar).

Still, to help make your customer’s mini- or micro-car safer, be sure to check the inflation pressure at least once a month. Some dealers are already offering free air campaigns at certain times of the year, especially just before peak driving seasons. As you can tell, proper pressure is very important with these down-sized rides.

Do you know what you need to know about aligning such small cars? Is your alignment rack the suitable length – or width – for a good alignment job? What about tire changers and other equipment?

In theory, nothing should change, but it can’t hurt to run a quick check to make absolutely sure your shop is ready to handle this new breed of transportation. These are some of the cars you’re going to be seeing.

Next time you see your tire supplier rep, ask about the wisdom of stocking a few extra smaller tires as the time nears for the rollout of even more micro cars in 2010 and beyond, like the 2010 Ford Fiesta, said to deliver 40 mpg. No word on tire sizes yet, but the curb weight is just 2,250 pounds, so it, too, will require a smaller tire. Chrysler owner Fiat, too, will be bringing in a small model next year.

It’s still early in the game so there may be a few more surprises in store, but for now rest easy and enjoy the ride.