the fit will be decided by the gap between the forks the wheel is in ,if you have a thin wheel a wider wheel wont go in ,probably easier to replace the lot and keep the old one as a spare incase you get a puncture
a bigger jockey wheel may need a bigger clamp if the diameter of the "pole" isnt the same as your old one.
i'm going to upgrade mine as well ,half sunken thin wheels are a pain
I've had them on and off on the campers over the last couple of years. On my Conway Challenger I fitted it, then took it off again after a couple of trips 'cause it was just too close to the ground. I also found that one needed pumping up every time I used it!
I've now got the one that was previously on my parents' caravan on the Conway Cardinal. That one only needs pumping up occasionally and fits reasonably. Only problem is it won't swing under the brake rod once the camper is hiched to the car, so I have to fiddle about to make sure I can raise it before the camper is hitched up. I used to be able to just lift the front of the camper by hand and swing the wqheel round but medical problems prevent this at the moment so I either get someone else to lift the front or just jack up the front on the jockey wheel, drop a steady to support the weight, then lift and swing the wheel into line.
Replacing the lot is the best way to go. Changing a wheel is a pain.
Ours has a PSI of 60. Beware, pneumatic wheels are heavier than the solid tyre and need screwing down very tightly when towing. Our wheel has dropped down and the tyre punctured twice now. (They are not designed for travelling at 60 mph).
So now we remove the jockey wheel completely when hitched.
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