Apart from the obvious requirement to change to 17-inch wheels as well as your chosen tyre, there are legalities to be considered here, and they can vary from State to Territory, so you need to check with your local authorities before committing to any change like this. However, broadly speaking, you can increase your wheel size by up to two inches, provided you don’t throw your speedometer out in the process. You also need to stay within a certain percentage of the car’s original rolling circumference (the distance the tyre travels in one revolution) to remain legal. And there are the practical issues such as tyre-to-bodywork clearance.

However, on the surface the swap you’ve nominated should be legal and practical. The 2000 Lexus LS400 originally came with a 225 60/16 wheel and tyre, so your preferred option only increases wheel diameter by one inch. Also, by fitting a 55-series tyre, you’ve reduced the sidewall height (from the standard 60-series tyre) so the rolling resistance of your new combination will be less than one per cent larger, so shouldn’t create any legal or clearance hassles. Just be sure to let your insurance company know you’ve made the change. Be sure to check the accuracy of your speedometer after the change, too. A GPS speedo app on your phone is the easiest way to do this.

Big Lexuses, like a lot of high-end luxury cars, have a habit of depreciating quickly, making them great second-hand buys. Like any complex vehicle, of course, there’s plenty to go wrong, although Lexus electronics seem a lot better than a lot of the competition’s.

As for the battery packs, it’s conceivable that a 2008 model LS400h could be getting to the point where it’s battery pack does, indeed, require replacement. But having talked to a few limousine operators who run hybrid Lexus cars, some of them rack up huge distances on the original batteries.

In any case, hybrid cars are now beginning to land in recycling yards faster than their batteries are wearing out, so there’s a relatively good supply of second-hand battery packs if the worst comes to the worst. There’s no hard and fast rule for the lifespan of the batteries in a Lexus, so the best bet is to have the car inspected carefully before committing to the purchase. The money spent on an inspection might be a really, really good investment.

The most expensive new Lexus is a LS500h Sports Luxury listed at $195,500. For more info on the latest model, check out our pricing and specs page, and you'll find all Lexus reviews and news here.