Peugeot 3008 - Alternative to low profile tyres - Trajan
Can I dump my 18" low profile tyres which have done barely 12000 miles and which need replacing already for 16" alloy wheels and 16" tyres, and if so would the car have to be recalibrated for the smaller wheels?
Peugeot 3008 - Alternative to low profile tyres - bathtub tom

First of all, if you've 18" wheels would 16" fit over the brakes?

Is there a model of your car with 16" wheels? Your insurance would consider it a modification.

Put your existing and proposed tyre size into the calculator about two thirds down this site to get the difference: www.carbibles.com/tyre_bible_pg4.html

Peugeot 3008 - Alternative to low profile tyres - skidpan

Where manufacturers offer an option of different wheel diameters the tyre sizes are always carefully chosen to ensure that the overall diameter is identical (as close as possible anyway) so that the gearing, speedo, ride height etc are not affected.

But even if the 16" wheels will fit over your brakes your insurers will consider this a modification. If you can prove that your chosen size is a standard fitment on another model in the range they may possibly charge no extra but you need to inform them. If you don't and have an accident they will use it as an excuse not the repair your car or pay you out.

For example, my BMW was fitted with 17" wheels. One model down the ladder was fitted with 16" wheels and my insurer (Aviva) was quite happy to let me fit those with no additional charge and noted it on my policy.

Peugeot 3008 - Alternative to low profile tyres - MrEckerslikefromRamsbottom

Ford put the available wheel and tyre size choice for that model, and recommended tyre pressure for each choice, both in the glovebox handbook and on a small plate at the bottom of the passenger door pillar. Perhaps Peugeot may have such a plate. (I didn't notice mine until I'd been driving the car for six years).