Google "tyre upsize calculator" and see for yourself. The variance between default and new tyres should be within 2%, so ideal upgrade size is 195/60 R15 which gives 1% variance. Since that size is not available these days, next best option is 185/65 R15 which gives 2% variance. Anything else will be higher variance and is not beneficial long term. Recommended tyres are Continental CC6 (Made in Malaysia), Yokohama GT AE51, Yokohama ES32.