It is rare for a car to steer from the rear but can happen. It is generally a traction imbalance. First thing is to swap the problem rears left to right to see if it goes in the other direction. Also ask yourself if the “pull” in the other direction on deceleration is actually that it is just stopped pulling left. I had a car do that because the Super Fuji diff was on the way out and a non slippy diff car doing it because the tyre was delaminating. Non of these should be the issue here because the car drives straight on the original rears. So check carefully, the profile of the tyre against another one. It is possible to wear a “nap” into a tyre (and quite common) so that it does want to steer in one direction. As the front left generally takes the most wear, and far more so than the right, then putting that to the back would potentially make the car want to go left.
I’ve had this myself on an NC with mismatched rear tyres.
I also remember a report of it on a brand new NC which destroyed the LSD. Eventually it was found that on delivery from factory to dealer one of the rear tyres was damaged. The dealer had replaced the damaged tyre with a matching Bridgestone. Although the tyres were supposedly the same the originals were Japanese and the replacement was manufactured in Europe. The tread patterns were very slightly different as were the compounds. This was enough to cause the problems. Unless the tyres are exactly the same they can have different charecteristics.
Check the date codes on the tyres. It is possible that a ‘set of four’ tyres may not be the same. Might have the last of one batch and the first of another. The driven wheels need to be matching.
I can’t see the point of “rotating” tyres myself.
Fronts tend to wear out quickest, (on front wheel drive cars) so a set of new go onto the back to provide better grip under braking, and rears onto front. (Only rotation i have ever required)
On my MX5 (NC) they tend to wear out the same for all 4 That even with track days, but then I try to drive smooth to the limit of grip without tyres protesting
I always like to buy a full new set when I’m ready for tyres and make sure they are all worn down evenly. I can probably make a set last around 5-6 years (no tracking) if they still perform ok, about 5k miles annually.
In some cases, diagnosis of the wear patterns on individual wheels from an UN-rotated set can also help show up nascent problems developing, such as sticky brakes, worn bearings, inflation or alignment issues .
Each of these has a different characteristic visible on the tyre concerned.
Sometimes it takes an expert eye to identify a lurking problem.
However quite often it is glaringly obvious once the (mostly normally out of sight) wheels are off the car!
The moral is to check tyres regularly, taking a clear tread photo of each one for future comparison. The camera rarely lies.
That s sorted it thanks Ian
Was it the back to front straight and front to back crossed over that sorted it?
Yes mate,had swopped front to rear & diagonally so swopped front side to side and now ok !