Recently got a set of wheels secondhand to use on my gravel bike. XTR M965 hubs which I think are 8/9/10 compatible.

I’ve tried both a new Tiagra 10sp HG500 cassette and and 8sp HG41 on it and both are catching the spokes and locking out the freehub when tightened.

I tried to space with a spare dork disc I had around but this was no use and the locking would not fit as threads would not engage. There was no other spacers wit the new Tiagra HG 500 cassette.

Do I need to buy another spacer or is there something else I am being ignorant of?

Sounds like the wheel isn’t dished right.
Edit: It’s easy enough to check, measure the distance between the rim and the driveside seatstay then turn the wheel round (Cassette on disc side) and measure again, the disance should be equal.

Something is wrong. You shouldn’t need a spacer for either of those cassettes.

Dropped the seller an email to check if I am missing a spacer, wheels not recently built so I’d have thought that if a dishing problem this would always have been an issue?

Any way of checking if it could be dishing? Would it look off centre when mounted in the frame?

Have you tried without either cassette in the bike to make sure it is the cassette that is the problem?

Also, when the wheel is in the bike properly the rim should be centred in the frame.

See my edit, yes it would look off centre in the frame, closer to the driveside.

Just had another look. Wheel looks central. Spokes only catch at the hub flange area. The more I look at it the more I am convinced a thin spacer is needed as finger tight on lockring the freehub still spins and there is a little movement in the cassette which is causing if to rub. Only locks up he freehub when fully tightened.

1mm spacer needed on 10spd cassette.

But tbh its more a case of whatever works, as long as the cassette doesnt wobble and it clears the spokes youre golden.

10 speed road cassette needs a 1mm spacer. Sorry the word Tiagra didn’t register for some reason!

1mm spacer needed on 10spd cassette.

HG500 doesn’t

1mm spacer needed on 10spd cassette.
HG500 doesn’t

I have read that Tiagra doesn’t but am wondering if it has changed with the latest version?

A spacer is a couple of pounds so I guess is worth a go.

I have read that Tiagra doesn’t but am wondering if humid has changed with the latest version?

Nope

HG500 doesn’t

The OP’s problem suggests otherwise…

The OP’s problem suggests otherwise…

The OP’s problem suggests that something is amiss with the wheel.

Is a Hg500 cassette riveted together? If so the rivets will foul the spoke flange, Xtr hubs are meant to run a spidered cassette, you could file the heads off the rivets and slide the cogs on individually or buy a higher end cassette.

Filed rivets but still slightly catching, definitely on the cog. Will try a spacer (seller is going to post me one) and if this fails get a higher spec cassette.

Quick visit to the LBS has revealed that a spacer was required after all. All seems to be working as it should be. Thanks all for the input.