New front tyres - wheel wobble at 80mph

Sounds like balance. First thing to try is to swap front and rear over, see if the vibration moves with 'em.

Yup.

almost certainly need an accurate rebalance. Modern fixed machines go out of calibration on a regular basis, no doubt a mobile one will get well shaken about and go out of whack even easier.

Like I said was fine with old tyres.

And machine looked a bit battered. To be honest, the guy who did - never met anyone sounding so thick in my life...

As has been chronicled in my various threads over the last year or so, my mate Gary has a tyre fitting machine so he does that for family and mates including myself and none of us have had a wheel balanced (he doesn't have a balancer) with no adverse effects at all on a wide variety of vehicles over many years. Those include his and his wife's two Audis, a couple of VW's at different times in the past, Golf TDi, a Seat, Land Rover Discovery, his mother in law's Puma, a Citreon AX, Peugeot 106, my Focus....no doubt many others I don't even know about.

I've had three rounds of tyre swaps on the Focus alone in the last year including fitting the snow tyres in the winter and then going back to summer ones in the spring, swapping the knackered front Goodyears for Toyos and the old rear Firestones for Kumho Ecstas. No wheel wobble at all on any of them apart from what turned out to be a buckled rim which should have been sitting in my pile of stuff ready to be weighed in for scrap because I knew it was buckled but accidentally got a tyre fitted to it.

So I'd be tempted to just remove all the weights the tyre fitter put on and see what happens before you pay for another round of balancing. You might find it's perfectly fine and save yourself a few quid.

I don't know if modern tyres are so well made now they don't often need balancing or maybe so few people even try running tyres without balancing because any tyre place will do it as a matter of course that they don't realise it's not always necessary.

I also think much of the problem with wheel wobble with cars in the past was down to play in wheel bearings, mainly the old type where you had to just nip up the hub nut and then back off a bit to leave some slack. Any more than the merest smidgeon of slack and the wheel can start oscillating if anything is out of balance. Modern sealed unit taper roller bearings with the hub nut torqued up to several squillion ft lbs don't seem to suffer from that unless of course the bearing eventually knackers so any slight wheel imbalance just gets damped out.

New, good make tyres scarcely need any weights, cheapos frequently need loads. So the cheaper the tyre the more important a correct balance becomes.

Did an experiment maybe 10 years ago.

Brand new bare rims, maybe up to 5g inbalance. Add manufacturer supplied bolt in metal tyre valve, around 10g inbalance, Fit tyre, inbalance up to 25g.

(16 inch Michelin Pilot Sport on BBS rims)

Seconded.

Nobody has mentioned the paint dot yet. The tyre manufacturer will have put a dot of paint on the tyre right on the lightest part of the circumference. You install the tyre with the paint dot at the valve stem, to minimize the need for balance weights.

Except that every tyre I've had installed for decades now has been by a fitter who has ignored this aid to balancing.

John

Trained fitters DO know about it, however, since tyres are usually a 'distress' purchase then most people go to the cheapest place, they don't tend to have tyre fitters that go on training and refresher courses.

IME, they don't even know about it. I always point it out to them.

I've got alloy wheels with pale green paint dots on them.

some wheels have a marking to show the low spot, the tyre high spot marking (usually the red dot) should be put adjacent to this.