I have now borrowed a 165/65/15 to test, same as Dave Cymru.
The chassis is from Herald 13/60, quite a late model that is on an 'L' plate - possibly it went abroad initially before being registered here.
Although this size tyre worked for Dave, it does still touch the frame when fitted both sides. It restricts about the last one eighth of a turn.
However, the front springs on my car have not been lowered yet. I think I will need to remove about 2.5 " from the front ride height - since the back has 3" of lowering blocks and a swing spring fitted.
At the moment the point of contact with the chassis is at the top of the frame section - as in photo 2 and 4 above. So logic dictates that with lowering, this point will rise above the frame into the bulkhead area which has already been heavily modified.
Also these tyres are brand new with full tread. A part worn tyre with just the edge of the shoulder worn away a few millimetres would probably clear o.k anyway.
So that's it for our car, 165/65/15 it will be. may have to review the decision after chopping the springs though.
Paul.
Even more tyred..
Threaded Mode
