[Pelo Cat]

So it appears I have a slow leak on my passenger side rear tire, hence why earlier this week the pressure was low on that tire (thought it was someone messing with that tire in a car park, turns out not).

Today message came up again, down to 1.7 pressure so filled it up asap, and now need to think about what I am going to do...

A) just replace the one tire and put off other choices until later (such as buying a new set of rims with summer tires and then this autumn put a new set of winter tires on these rims and use them straight away, reducing aging of the rubber. Cost likely around £250 for the tire, then the new set of rims with tires 2.5 to 4k I guess in about a month...with winter tire costs deferred until Autumn so 1k at that time but then sorted.
B) put winter tires on the whole set now, saving the cost of the one tire and having a set ready for next winter, even though they will be stored and 'age' for 6 months before use again as it won't be long now before one can't use winter tires any more and would need to switch tires (a month maybe max?). Means I have saved the cost of a tire but have to buy 4 winter tires now and then in very short time, need to buy the summer tires and rims. (1k for tires now, 2.5 to 4k in a month)...
C) other option I am not thinking of? (not much of a fan of trying to fix/seal the leak but maybe others have experience and find it not too bad? (can one even on a run flat)...

No visible damage to the tire or rim so guessing it is something on the tire tread somewhere with a nail, etc...hoping it is not some damage to the rim I don't see that would add to the money or cost issues.

That sound about right? Any other thoughts/Options?

Wanting to get a bigger set of rims for the summer, current rims are good for the winter and are 18s, same size tire all round. Summer looking to go 20 inch rims with offset sizes likely needed.