I posted this in the Maserati forum as well I am looking for all season tires for my Ghibli SQ4, front 245/32/21, rear 285/30/21. I can't seem to find anything for the rear. Options: 1. Increase aspect ratio to find a tire (285/40). Do I need to increase the front aspect to match? Is this not recommended, and would the car need recalibration to match new size. 2. Get 20" wheels - expensive and would I need recalibration as above? 3. Use a lesser quality tire (anyone ever heard of Arroyo?) for the winter and change with the seasons. 4. Don't drive the car under 40F. Not what I want to do. Please help Jim
Michelin PS4S are available in those sizes Michelin AS4 are available in 245/35/21 and either 275/35/21 or 295/35/21. Given your intent to drive in the cold I would choose the skinnier 275 option for the rear. Overall the small difference in size probably won’t confuse the traction control or ABS but no guarantee until you try.
Mikey, thanks for the reply. I have learned quite a bit about tires in the last days. The PS4S are listed as summer, so that is my issue. The AS4 275/35/21 seems to be closer in diameter to the original (2.5%). I am going to look at them.
The PS4S is not one of the summer tires that is tragically bad in cold (DRY) weather. They certainly have less grip, but are at least predictable. I am not recommending that option, just a data point...
I am in somewhat of the same quandary as Weaselwee. I have a 2024 Mercedes S63 AMG e Performance. It also has 21” wheels. To further complicate matters, the tires are HL rated. I have not been able to find a winter tire for it. The car is equipped with PS4S tires from the factory. As JoeCab states, if the weather is cold and dry, they do fine. However, in the snow or slush, they are not good. And, it seems as the temp drops, they get exceedingly ‘greasy’ so be prepared to do some slipping and sliding. If you get little snow, the PS4S will work just fine.
