I have a 2004 S430 MB with AMG package. I just put on a new set of Goodyear F1 Eagles. 265/45/zr18 on back and 245/40zr18 on front. Car specs 30 psi in front and 33 psi in rear. Tire spec indicates max psi of 50. I put 36 psi in back and 33 psi in front. The car says I have low tire pressure at this setting. What psi is correct or what psi should I use? I would like as much life out of these tires with good handling as possible.
Car specs govern, as long as the they don’t exceed tire’s max. Especially with such low profile high performance tires, I would follow MB’s recommendations to the letter (check first thing in the morning, before any driving). Are these the size for which MB’s recommendations were made?
You should run 30 up front and 33 in the rear if the car specs that with those size tires. You definitely don’t want to increase the pressure 6 psi in front or it’s going to understeer like crazy in fast turns. If you want greater tire life you’ll have to change the tire type to something with a better wearign compund and go easy on the aggressive driving.
Make sure you have a good quality accurate tire gauge! If you’re using a pecil type gauge toss it out and get a good quality dial gauge.
There is no tire recommendation here. There is only a tire maximum. There is a difference!
Tyres don’t come with recommended pressure. They have a maximum pressure listed on the sidewall. That sidewall pressure only means that if the car’s recommended number is higher, those tyres are not safe on that car and are designed for only lighter cars.
If the car is saying you have a low tyre then likely it is having trouble sensing the pressure and something it wrong with that system.
I should ask if you are sure you are getting the correct pressure in the tyres and that you are measuring that pressure with the tyres cold, not after running them on the free way for 20 miles.