Moved up from my L322 last summer to an L405 SDV8 AB. All in all a fairly decent motor, but the ride was nowhere near as smooth as the 322. Contacted the dealer I bought it from and they collected the car and replaced the front lower suspension arms and anti roll bar bushes FOC. This gave improved handling, however it was still a fairly harsh ride which I put down to the 22 inch wheels and dreadful roads where I live. Down the line a couple of months, a pothole gouged out a chunk of rubber to the nearside front sidewall exposing cords. Took the car to a very respected independent tyre fitter I use for our commercial vehicles and they said regardless of the cut, both front tyres were close to the limit on the inner edge and recommended replacement of both. Job duly done, they carried out a Hunter four wheel alignment check free of charge, but with a nominal fee for adjustment. Drove the car away and noticed a slight improvement in ride quality. None the less, still not acceptable and nowhere near as smooth as the 322. After a lot of research, and browsing fullfatrr I could see ride quality and suspension issues were quite common. Then the penny dropped. I remember seeing the chap who carried out alignment checking the tyre pressures and could hear some air going in. I subsequently checked all four tyres first with a digital gauge and then double checked with a professional gauge I have on my compressor. All four tyres had 46 PSI. This is way over the top, especially for the fronts and particularly on 40 profiles. Recommend pressures for normal use 36 rear and 33 front. Net result, the ride quality is totally transformed. Moral of the story, don't assume the trade always get things right. I can only assume he looked at the max pressure on the Contis which is about 51 psi and settled on a slightly lower figure all round. A little peed off as it's wasted a fair bit of my time and this did lower my opinion of the car unnecessarily.

Glad you got it sorted, but Your TPMS wasn’t working as well then ? 2021 L405 Vogue SE 4.4 V8 DIESEL ~ #17

Hi
Hope you don't mind me butting in.... Does the TPMS read over pressure as well as under pressure?
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Mine does on start up - flashes on the dashboard whether it’s set for light load etc - you can also go directly into the menu and it tells you the pressure for each tyre. 2021 L405 Vogue SE 4.4 V8 DIESEL ~ #17

Doesn't have TPMS as far as I'm aware. Certainly the valves are standard rubber type but monitoring might have been useful in this instance !

Has anyone noticed that recommended tyre pressures change whilst driving? I can only assume the software detects the type of driving e.g. motorway vs. town traffic, and adjusts accordingly.