360 M handling problem

I see you have a mixture of tyres (manufacturers), did this start when the rears were replaced (assuming you had them replaced), but my money would be on ball joints

 

Have the ball joints checked for wear first, but sounds like it could be tyre related.

 

I agree with Malcom, ck the balljoints but never, never mix tires on any of the modern cars. You can wind up with some very evil handling characteristics.

While you are changing tires have an alignment done. Some of the cars came with the alignment very poorly set.

 

I second the tires - if they have different treads (which they do) - your car will feel very squirrelly in a straight line. You can even find this with the same tires - if the back is newer than the front or in reverse.

I had the same issue on my 355 spider - and I will tell you it is unnerving - feels like it sways to the right and left at speed.

Go get matching tires - and you will be set.

 

All of the advice you have received is very useful. However, a strange phenomenon can occur as tires age and wear. You do not say how old your tires are on the front. Sadly, as some high speed tires near the end of their useful life, the internal radial plys begin to separate causing instability at speeds around 80 mph and above. This happened to my Porsche 928. If you notice the loss of a wheel weight along with the stability problem at speed, you need new tires. Cheers, Ken in PA USA.

 

I am almost certain is the tires...A buddy of mine mixed tires on his 2001 Spider and as some posted earlier freaky things started happening while on a straight line...after tire replacement he was back to normal. I must add he had put all seasons Pilots in the rear.

 

Recently changed the rear tires only on the 360 from P Zero Rossa to Nero's. The handling went from not so good compared to the Michelin Pilot Sport to terrible. Twitchy and unstable.

 

Do anyone knows the cost of replacing the ball joints?

 

Definitly get a matching set of tires. Have your front toe checked too.