increasing tyre size

[exclusiv.]

Could possibly knock your speedo out of true

[DeaniFLHT]

I wouldn't go higher profile. That will throw the speedo out. It will under indicate speed/distance.

Look for tyres of the correct size with a decent depth of rim protection built in. Or perhaps go for wider tyres e.g. a 255/30R20 should give a similar rolling diameter to a 245/35R20.

[0011728]

Also bear in mind that any deviation from the factory specification for tyre size will also affect the speedo of the vehicle

[Lance]

Why not lower the car rather than play with tyre sizes?