You do what you do or want and don't risk it for a biscuit. Way too risky for the risk adverse.
Loss adjusters might well check, might well not be totally daft & have a bit of knowledge.
'Stretched tyres' would be a total no no for me, and should maybe be for MOT,s and road side checks & insurance underwriters.
?
Is this about Insurers and Tyre Approval / Certificate or Confirmation and approved standard OME Tyre sizes.
If the car has approved sizes / tyres - wheels of different sizes but the same Speed / Load ratings can the different axles have tyres / wheels from these sizes?
Audi option of wider on the front and rear, BMW, Mercedes, Porsche, Audi etc etc etc larger rear than front.
Skoda Enyaq, ID4 etc Staggered Tyres / wider/ larger rear than front. Honda Electric, BMW i3 etc.
Can you take the Staggered wheels and change than for matching front and rear winter time? When you need Snow Chains?
When you want to carry a spare that will suit front & rear!
Is it just a matter of declaring mods then as we do with Off-roaders or other cars, Modified or kit cars etc.
215 front, 205 rear, matching circumference.
& the orange JImny,s never came with tyres the size this one had on. 235,s.