Z alone predates Y and was 149+. I am seeing ZR rated performance tires for sale now. Why not label it Y? I don’t know.
Tire speed ratings;
V - 149 MPH
Z - 149+ (out dated)
W - 168 MPH
Y - 186 MPH
(Y) - 186+ MPH
The Hellcat comes with (Y) speed rated tires, the parenthesis indicates the next level in the “Y” rating. The Z rating was assigned erroneously when it was believed the highest needed speed rating had been achieved now resulting in the alphabetical sequence out of order.
I unintentionally got a friend’s Oldsmobile up to 110 driving I-10 in Texas; the road was empty. I just kept my foot on the gas, didn’t notice the speed. He noticed, told me it was the first time it had been driven that fast. I was shocked, let up: it didn’t respond immediately. Had I had to swerve, I couldn’t have.
I’ve read the Crown Victoria Interceptors have governors that keep them from running at the speeds they do in police cars. I thought the same was true for other performance cars.
You mean increase the torque on the lug nuts? She couldn’t buy a torque wrench?
Unlike Montgomery Avenue. I was bicycling that stretch about 4 AM today. I had it to myself.
The 300 F was capable of running 137 ON THE BEACH. That was running on wet sand, It was capable of much more on pavement. WE regularly exceeded 100 mph back in the 50s. No speed rated tires and bias ply to boot. We just put 40 pound in the tires and hoped for the best.
The 51 Chrysler Saratogas that were entered in the unlimited class of the Mexican road race were 160 mph cars.
Didn’t a Lincoln Capri come out ahead in those races?
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Those Lincolns captured 1st, 2nd, 3rd, and 4th places–two years in a row.
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Interesting thing about the P71’s. They may or may not have governors/electronically limited top speeds) depending on the axle ratio and the material of the driveshaft. P71’s with the 3.55 gears and the aluminum driveshaft are limited to 130 MPH. With 3.27’s and aluminum driveshaft, there is no limiter in the ECU as the critical speed for the driveshaft in top gear is 145 MPH and the car simply can’t go that fast. P71’s with the “metal matrix” driveshafts typically don’t have their top speeds limited and max out at around 125-130-ish MPH depending on the year.
The difference in performance between a civy Crown Vic and the P71 isn’t much. There are many urban myths surrounding P71’s. Most are false. They aren’t particularly fast/quick cars.
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Back in the early '60s, the county police in my old county seized a yellow '61 Ford Convertible in connection with some sort of major crime. Because it had a 4-barrel 390 engine under the hood, they decided to keep it, rather than selling it. It was pretty fast, and they surprised a LOT of speeders when they were pulled over by that unmarked car.
As a young boy I would spend my summers on my aunt and uncle’s farm in Eastern Montana. Among the many old cars we had around there was a beautiful 53 Capri. I asked my cousin why the car was in the “junkyard”. He said uncle’s brother had bought it new, then sold it to uncle 5 years later. By the time the car was 25 years old the interior was a little rough but it still ran like a top. My cousin had it on a country highway and hit 110mph when the timing chain went. And since this was an interference engine that was the end of the Lincoln.
There was a puzzler on front tires of dragsters going flat. I think it was at 200 mph or so the schraeder valve would open due to the centrifugal force.
I once calculated the G forces tires go through at high speeds. It’s pretty amazing.
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I keep caps on my valves just in case I gotta go that fast sometime.
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ZR is used in the size of the tire to indicate it is capable of over 149 mph. I.e. 225/45ZR17. The actual speed rating is with the load code, I.e 87Y.
So you could have a tire that is 225/45ZR17 87Y. You can also have a 225/45-17 87Y. Apparantly the ZR is not required anymore.
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Th` Lincoln won the stock class. The Chryslers were in the unlimited class and finished 3rd overall behind two of the many Ferraris. Far , far, ahead of the Lincolns.
Th` Lincoln mechanics sent all the modifications back so they could be added to the parts catalog as “export” parts. The Chrysler mechanics didn.t, they thought thty had a shot at first overall.``