Will the 225's fit on the rims ok? They won't necessarily give more grip, as they will lower the pressure on the contact-patch on the road surface. Wider tyres can trap water badly in the centre, causing aquaplaning. The 225's may have a higher rolling-resistance and make the car drink a little more fuel. IF they give more grip, then WHEN they actually let-go, an inexperienced driver may find they break-away much too fast to control.

Yup, 20mm diff. The 225mm tire has a larger contact patch and in most instances a greater load carrying capability. But the great section width can also create more resistance which can decrease your fuel economy. But be careful here, Richard, you really need to stick with the section width size that the designers and engineers of your automobile determined would be best. Otherwise you could be asking for trouble.

That there is a 20MM difference in width, you could cause a real problem, maybe.

What about them?