I have searched… and all the threads I can find here focus on matching the maximum rim size (i.e. 22") with ultra low profile tyres… but I drive on badly pot holed roads, and, for safety reason, I actually want to increase the amount of rubber between my rims and the road.

I know this may look daft to someone with 22” rims and 30 profile tyres but trust me, this setup would not last 10 miles on the roads I sometimes drive down.

Currently I am using 235/65/17 tyres, these give me 6” of rubber between rim and road and a total top to bottom diameter of 29.03".

If I could fit 245/70/17 tyres on my existing rims I would gain 0.74” of extra rubber between my rim and the road, but total diameter would be up to 30.5”. Total circumference, and hence speedo error, would increase 5.1%.

Basically I want to know what is the biggest diameter tyre I can fit on a standard 17x7.5" rim before it rubs on my 2006 X5 3.0D, rear only self levelling air suspension, non flared standard wheel arches?

Whatever I do I will do equally to all four corners so there should be no issues with DSC and ABS etc. I know that my speedo error will increase, and I know my handling will suffer, but it may save me a few bent rims and long walks home so I would like to consider the options.