I would say it shouldn’t affect the steering wheel position or the alignment, only if they’ve adjusted something there.
What you may feel different is feedback from the front wheels (steering) if the worn rear tyres/wheels fitted there are unevenly worn or out of balance.
Do check the set pressures by the fitters, these are in my experience set higher after tyre fitting, should be 29psi.
Just to add I would advise on fitting a full set and rotate annually for even wear, just my way of replacing tyres.
If you have uneven wear I’d advise on getting a full alignment check, use a trusted MX-5 specialist.
You can get wear on tyres that works a bit like nap on cloth (think snooker table) that will pull a tyre in a certain direction.Easiest thing to do is swap the tyres back.
The rationale for putting new tyres on the back stems from the principal that new tyres grip more and that the “extra” grip on the front will shock drivers and cause oversteer etc. I think in most cases you can ignore that, especially with modern ESP systems.
It could of course, quite legitimately, be something else. I wouldn’t expect any garage would adjust tracking without wanting to charge you for it.
I would expect the rear left had worn more on the outside edge and the right potentially on the inner edge and that diameter differences and crown is pulling the steering. Swap the new tyres back to the front and see if it goes away.
Precisely what I experienced a few years ago.
Put new Dunlop Sportmaxx 2s on the rear and swapped existing Continentals from the rear to the front (plenty of tread and no sign of uneven wear). Sterring was a nightmare until I put the new Dunlops on the front and Contis back on the rear.
The main reasons for replacing front tires were because they were getting uneven wear and I was getting a vibrating noise from the steering.
NickD - makes a great point about tire rotation and modern ESP systems. As Costco insisted on this rotation policy - I will use an independent garage in the future.
I had a 3D wheel alignment done and hopefully this should cure the steering vibration noise and uneven tire wear issues.
I take on board everyone’s recommendation to swap the front and rear tires back. Just wondering why it is advisable to get a wheel alignment done after fitting new tyres?
When tracking is adjusted, the correct way to do it us to adjust both sides evenly until correct.
The lazy way to do it is to adjust one side only.
This will work but will leave the steering wheel off-centre.
Of course, it could be incompetence rather than laziness with both sides having been adjusted but not evenly enough or maybe even ignorance of how it should be done.
Take it back and complain?