1995 Sc400 Rpm

[garyk]

I recently purchased a 1994 SC400 with 91000 miles. I really enjoy this car and have a couple of questions for the board. First of all, at highway speed, say 75mph, I have noticed that the engine rpm is about 2750. On our Dodge Caravan with a 3.3 litre V6, the engine purrs along at 2250 rpm at 75 mph. Why would a V8 need a higher rpm at highway speed compared to a fairly peppy V6? Secondly, the car came with Bridgestone Potenza tires which seem kind of noisy at highway speed. Is this normal or should I invest in some new, quiet tires? Recommendations please.

[jzz30]

that rpm sounds about right because going about 50 mine is about 2000rpm but just to make sure make sure your overdrive isnt off. and i dont know about the tires. i have bridgestone RE730s and SO-4s on mine. the car isnt as quiet as my LS but they dont compare

[grnstreak]

The highway speeds are all dependant on your gear ratios.

The SC400 is geared toward sport luxury, whereas the minivan was meant to conserve as much gas as possible. The minivans gear ratio does sound a bit high though. The gearing on the 400 sounds normal.

The tires you have a performance oriented tires, and are made for higher speeds and werent really considered for comfort.

Keep the tires, turn up the radio and enjoy the SC400 as is :D

[garyk]

Thanx for the advice. I appreciate all of the terrific information that I have found on this board.

[BMAN1113]

I had a set of Dunlop S5000 Z rated tires. They were sort of loud as I think alot of the super performance tires are. I decided to go for more of a sport/ touring hybrid and just bought a set of Michelen Energy MXV4's. I read up on these tires before I bought them and noticed that alot of people bitched about cornering performance, but all agreed that they were very smooth riding. Seeing that they were still rated for 150mph, I decided to try a set. I have been pleasantly surprised with the smooth ride as well as the unexpected performance... that people said I wouldnt be getting. I think the handling of these tires are very comparable to the Dunlop S5000. Maybe slightly more roll on cornering but nothing out of control. I like driving my car on road trips... on the highway, so I decided to go for a smoother ride and these gave my car that Lexus silkiness again. They might look a little strange on the car at first, as I was dissapointed when I first saw them mounted. But after a few days of breaking them in, I'm convinced that the side walls kind of "squooshed-down" slightly... like they underwent a breaking-in process. Bottom line, I really like them. I also like the 50k mi rating guarantee that came with them. Seeing that I only got about 15k off of my Z rated Dunlops. Keep in mind that no-one will give you a mileage guarantee on Z- rated tires. And SC400 are notorious for burning through the rubber. These cost me $135.00 each from Discount Tire. C-ya.