Overkill on Speed Rating
 

I think nowadays all the tire manufacturers are producing tires which have excessive speed rating. Do I really need a tire that can sustain 130mph or more in U.S.?

I just ordered a set of Bridgestone RE950 (H Speed Rating) for my 99 E430 Sport. The sales associate told me that my car needs a Z speed rating. I told him that I hardly ever go over 100mph. Even if I do, it would not last for couple seconds.


Car Nut
99 E430 Sport

H-rated is fine.
 

I would never go below an H-rated...but its safe to say if you don't go above 120+, then H-rated is fine. The reason I leave about an 8-10 mph gap, is certain tire require you to add a certain amount of air in the car's tire if your going at higher speeds. All they indicate is the max speed of 130, but that means if your car has the highest recommended amount of air (in PSI) in it. for that reason, on the stock PSI, I would keep a 10 mph distance.

Don't drop too far below the OE speed rating for your car. Speed ratings are based on heat resistance. Your car's ability to generate heat in it's tires is substantial. High cornering loads, sustained 100mph running in high ambient temps, etc.

I would NEVER put less than an H-rated tire on your E430. BTW, we ran the RE950 on our 1998 E300, and really liked them. Their rain traction is almost unbelievable.

Make sure that the load rating is okay, keep your pressures right, and you'll be just fine. I do think that the E430 is limited to 210km/h anyway.

Legalities have a lot to do with mfgr's. installing speed-rated tires.
They have to install tires to match whatever the car is actually capable of doing.
Someone told me, and I am inclined to believe it, that in some places, you could actually fail a safety inspection with "downgraded" tires.
Some time ago, a reputable, local tire dealer refused to install anything other than v-rated tires on my Mustang 5.0.

Speed ratings also reflect the tires ability to deal with the torsional force generated by acceleration, braking and cornering ... it's not all about top speed