Hi,
2014r1200GSA
New tire are both 35psi old were 42 & 36psi
not surprised about so few responses - your opening question was ambiguous at best, and the topic is a minefield of complex elements to grasp and even harder to disseminate - here's 30 mins of stuff I've written up, most will complain about, and far fewer will act upon
vehicles (cars and bikes) come from a vehicle manufacturer with a range of tyres and recco tyre pressures they have tested and believe are safe/suitable/compatible - on bikes with advanced rider aids they then have to calibrate the system's brains and the maths based on tyres that are readily available and suit the bike and those systems
in the mix, tyre size, rim size, speed rating, load rating, compound, carcass design and construction etc. those basics, all need to work with and not fight the bike's frame / suspension / damping / weight and handling and safety system's characteristics
on occasions there are odd peculiarities on a given bike model and the manu works with chosen tyre manus on specific customisation of a base tyre that was available for any bike, and customise the carcass and or the tyre compound to try and combat foibles in the bikes behaviours (the first zzr1400 is one example, and I think the correct tyre gets a b designator to say this tyre is built slightly differently to combat some failing of the original bike. This bike manu bodge up, is not as uncommon as it ought to be !!!.
thus the manu have a set of tyres and indeed an intended vehicle use in mind and go about setting their bike to work inside these parameters - so if they say 35 front and 46 psi rear and set their own safety systems to work best in this condition - that's how it is - they do not and in my mind shouldn't bother to allow customisation of said safety systems for the the bike that they can't control
recco fit tyres for this bike will not say 35psi all round and even if the generic pressures of an allegedly compatible tyre recco 35 psi both ends - I doubt BMW recco using those pressures for this vehicle fitment and this tyre
so now we are heading into the unknown and unusual circumstances of rider instigated modification - its very common to see USA riders think car tyres are suitable for motorcycles - they are not and never will be, and most certainly should never go on a solo motorcycle. people making this modification should have the bike impounded and scrapped, and their license to use "public roads" removed
next we have tyre manus offering generic fitment sizes and about right tyre pressures - its not always a FULLY tested solution with the manu test riders in an exhaustive thorough 5k mile test. They sell and advertise tyres - and sadly no one cares any more about pretty much anything - if its round and black and you're not dead, it was close enough is today's attitude
that said I'm surprised the bike is alerting you to the small change, if it is, it's likely because you have ABS Pro (cornering ABS and traction control or the lazy manu set all bike warning's to suit an optional rider aid) and thus its expecting the tyres to behave a certain way to keep those safety systems operating within normal parameters - and puts up warnings when it doesn't think these are being met
if something is saying 35 psi both ends, I guess you bought sub-optimal tyres....
