DSM2GS400

I currently have a set of:
245/35/19 F
275/30/19 R
Tires on my GS400.
Was lucky enough to pick up a couple of nails in one of the rear tires. Was told because the nails were too close to the sidewall it was unrepairable. I ended up getting it repaired and was losing about 1psi per day...This was manageable and I would fill it up with air every few days. Over the pasy couple of day I have lost about 5-6psi per day. This is not something I want to deal with and I guess I need a/some new tires soon before the tire fails...

Of course I can change the one rear tire, I think I may change both tires though as getting a match for the tire in Toronto seems to be quite difficult.
So I was thinking about trying something new...

So here is question one...
I will keep the front 2 tires
245/35/19
But I think I want to go to a fat setup, car is not lowered.
Am I able to change the rears to 275/35/19?
I know its a larger diameter tire, the "allowable limit" is a 3% variance... This calculates out to a 3.09% variance...
Acceptable?
Or should I stay with the 275/30/19?

Question two...
I will keep the front 2 tires
245/35/19
Car is not lowered.
Can I use a 285/30/19 or 295/30/19? Diameter difference is within the allowable limit, but will I rub from the width?

Sltwtrking

I would not recommend running a taller tire on the rear for handling reasons. I would keep the rolling diameter the same (close to) front to rear.

The max width for the rear of your car is 285mm. The 285/30-19 should work assuming your wheel dimensions are correct. You will have a better selection of tires (matching sets) if you stick with the 275/30-19's though.