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Brown, I find 38 psi (cold tyre) works perfectly on my 19 inch rims. Mind you 38 works perfectly on my other car with 18 inch rims.
Agree Skylarking, the best feature is the dryness of the gas. I guess the providers will use Nitrogen from bottles which is the result of rigorous processing, rather than just drawing air from the back of the servo compressor.^ Yep, with some people it’s easy to sell ‘snake oil’ like product and make a few bob in the process. Lots of such products on yen market.
As for nitrogen tyre fill, I’ve had it offered to me by the up-seller at the tyre shop. I replied “seriously, air is already 78% nitrogen” and his shoulders visibly sunk just that little bit. Needless to say the up-sell attempt was over
As for “any real effect for passenger vehicles”, I’d go further and say it has little to no effect in most racing situations. And I’d suspect any nitrogen used in racing is a marketing attempt from the tyre suppliers to convince us that their “product” has merit.
[edited to add]
About the only real benefit of using nitrogen is that it contains no moisture and overcomes some perceived pressure change issues in humid locations. Such issues can be resolved by properly maintained compressors and dryers that removes any moisture from the compressed air. But seriously, many non enthusiast car people (the ones who race on tracks) would not be able to tell the difference in the handling of their road vehicle between 30psi and 40psi in their tyres; nitrogen or not
