Franco

why is it that my friends 2001 max tops out at 130ish(auto) and my 2000 max got up to 147mph(5spd) and was still pulling is there a different governor on them or something. also has anyone topped out there 2000 max 5spd?

Ludacris

iTrader: (11)

Don't know the answer to your question but where do you guys that check your top speeds drive so fast? I can't figure anywhere in an urban city that could allow you to get to 147 mph without obstructions.

Norm Peterson

Let me guess. Your friend's '01 has the H-rated tires as original equipment and you've got the V-rated 17's. The 130 mph or so is linked to the speed rating of the tires - "H" being 130 mph. V's are good to 150.

Norm

MAXinNH

Norm,

Not sure I understand your post...

Tire ratings are for safety, and have no bearing on actually limiting actual speed to the rating, right?

mdeal

iTrader: (2)

They govern the cars depending on the type of wheels that came on it.

young1976

uhm, speed governor set to match the speed ratings of the tires? Does his have 16" stocks? They are probably lower in speed rating.

Norm Peterson

Mdeal and young1976 have the right idea (and they beat me to it). Here's a little more detail.

The full designation of the standard 16" tires is P215/55R-16 91H M+S, so the standard tire is an H rated tire. The 17's are V rated.

It's all about product liability. The speed rating of the tires constitutes an implied limit on the top speed achievable by the vehicle. Beyond that speed, the integrity and safety of the tires is specifically denied by the tire maker. So the car mfr's typically control the maximum possible top speed for any given vehicle such that it cannot be made to exceed the speed capacity of the tires within the tolerances of measurement, system hardware/software, and factory conservatism (they might actually set the limit slightly lower, say at 127, to give themselves a little extra margin).

Since the technology to accomplish this end is readily available, if the car mfr's did not do this, they could be held legally responsible for any consequences. Consider the situation in which somebody experienced a failure of an H rated tire at 142 mph. The "shotgun" style legal proceedings that would follow would have a legitimate case against the mfr (and possibly also against the selling dealership as a separate defendant) for providing a vehicle with tires that were substandard with respect to the potential performance.

Norm

maxse01

I hit 149 last night in my max with 2 of my buddies in the car. Without them i could have gone over 150. Can't wait for the supercharger, gonna go for 160.

Norm Peterson

Don't be too surprised if it doesn't go much past the V rated tire speed of 150 for the same reason the H rated tire cars quit at around 130.

Norm

raynist

My car was the GXE 5speed. It came with 205/65/15's. I am not sure of the speed rating, I wonder what my top speed would be limited to?

Norm Peterson

I'm guessing that they are also H rated tires, so I'd look for 130ish.

Here's a more complete table of speed rating symbols in case the OE 205/65-15's were something else (if anything they'd most likely be S, T, or U rated).

Speed Rating Symbol
RATING SPEED RATING
SYMBOL (km/h) (mph)
B 50 31
C 50 37
D 55 40
E 70 43
F 80 50
G 90 56
J 100 62
K 110 68
L 120 75
M 130 81
N 140 87
P 150 93
Q 160 99
R 170 106
S 180 112
T 190 118
U 200 124
H 210 130
V 240 150
W 270 169
Y 300 188

ZR Over 240 Over 150

Norm

young1976

Hey Norm, you hit it right on the head of the nail. We may have beat you to the answer but you explained it perfectly. I guess I was too lazy, my bad. good info. Oh by the way, I'm assuming you like your 5 speeds... sig...

hehe

WILLSE

thanks for ur diagram but i am the friend that franco is talkin about i had 17 inch rims with the stock potenzas 225/45/17..... the tire rating means jack crap all the rating is... is that it is safe to that speed it doesnt mean that the car stops bc the tires wont let it! the reason my car wont go over 135 is bc the late 2001 models all were hit up with governers on them..... and i have a 2001 with the gov on it.... all autos r governed! the 5 speeds arnt..... its not the tires so dont say that it is!

Norm Peterson

Yup. Don't want my left leg to shrivel up from inactivity.

Norm

Norm Peterson

Easy now. Original equipment tire speed ratings aren't the only reason that Nissan or any other mfr will govern the top speed on their cars. But it is a common reason for limiting top speed, so given that the 130ish limit mentioned coincides so nicely with the H speed rating, it's as good a place as any to start.

If there's some other reason that requires a lower limit than what is consistent with the OE tire speed rating then the limit is simply set to suit whatever that other reason might be. Like something related to maintaining a certain maximum AT fluid temperature, for instance, which is in line with governed auto's but ungoverned sticks.

Norm