Ziggy - I suggest you refer to page 63 of the current rule book. It covers the rules for 1/10 scale On-road 4WD Open that you are calling Outlaw. It says the wheels/tires are 31mm. If you get the products from a source that are larger, they can be cut down to narrow the width to the ROAR legal limit. It is possible that you run in another association since you are in the UK. They might have a different limit than ROAR.