Wheel modifications

[barking]

Requesting some assistance, I will be requiring new tires in the not too distant future, so taking a preliminary look at modification.
Currently my ’04 CV8 is on stock 18’ wheels and tires.
Pros and cons of 19’ wheels, as far as I understand they fill the arches nicely but decrease ride quality, choppiness etc, require some recalibration. Is this all correct?
Wider tires, I understand you can increase to 255 on standard rims, would probable be looking at only rear wheels. Pro better grip in the dry, cosmetic and cons cost, ride quality, road noise. Is this all correct?
Sorry, I know the subject has been discussed before but I was looking for some combined input on one thread.

[The Jackel]

I have put 245's on the back and kept 235 on the front.

Had no problems with handling and ride quality.

As for road noise (can't here it with the new exhaust)

All on standard CV8 18 inch wheels

[V8HSV]

I have gone from 18" on 245 section to 19" on 245 but with 35 profile, using tyre calculators there seems to be little difference. However putting a 19" with new tread against 18" with worn tread against each other off the car & the difference is staggering, the 19" looked about 1 1/2" taller!

I do have some interference problems but then I am somewhat lowered & on coilover with different camber set up (turning whilst braking causes it to rub on top front arches) and I would not forsee any problems going for 19" over 18" on 245 section, poss ok with 255 or 265 section at the rear. The ride quality is not that noticeable between 18 & 19, I went from 36 psi to 34 psi for my honeymoon and it made it very compliant on Devon & Wales roads. More grip can be attained by camber set IMHO rather than increase tyre width.

[GSI_Daz]

You'll be fine to go to 19" rims if you stick on 245/35 tyres. The overall diameter will increase 0.35" or 1.3% so will not need any recalibration.