Another tire size question

[alabama_lowlife]

I've read a couple of threads on here which indicate that the stock tire size of a 521 was 6.00 x 14. This works out to a modern tire that has a diameter of about 23.7". I've current got 215/35-18" tires on my truck, this has a diameter of 23.9" which should be nearly indiscernible on the speedometer.

 

I'm wondering if maybe the 1970 521 had a different tire size? When I'm cruising along with the speedo reading 60, I have traffic stacking up behind me and people just dying to pass me. It feels like I'm going 50.

[datzenmike]

No, 6.00X14 or 175/70R14 23.65" tall.

 

It's drivers today. If your doing the speed limit they aren't. I suppose your speedometer may be out??? If you have mile posts on your highways time yourself. 60 MPH is exactly 15 seconds. Go 60 for 5 miles and average it. 5% out is only 2.5MPH at 50 MPH.

[datsunaholic]

Um, 15 seconds between mile posts is 240 MPH.  I don't think a 521 can go that fast.  Unless you meant quarter-mile posts, which I've never seen in the US.  Just miles.

 

60MPH is 60 seconds to the mile.

 

Most people are doing 70+.  Just 5 MPH under the speed of traffic will seem very slow.

[ggzilla]

Speedometers are always out. They have a +10 mph over tolerance right from the factory!!

 

Use a GPS Navi or smartphone gps tracker to get an accurate speed to compare it to. Then adjust it by replacing the driven gear that bolts back in the transmission.

[datzenmike]

Um, 15 seconds between mile posts is 240 MPH.  I don't think a 521 can go that fast.  Unless you meant quarter-mile posts, which I've never seen in the US.  Just miles.

 

60MPH is 60 seconds to the mile.

 

Most people are doing 70+.  Just 5 MPH under the speed of traffic will seem very slow.

 

Oh man, did I say that. :blush:  :blush:  :blush:   ouch.

[datto510]

speed x time = distance

 

distance/time = speed

 

distance/speed = ETA

 

B)

[alabama_lowlife]

I'll try the GPS speed thing, there are several apps for the iPhone that do that. I can always use it in one of the other cars to see how close it is to being accurate. Slow or fast, it's still fun to drive!

[DanielC]

Many years ago, I got a speeding ticket in my 521 on the freeway.  I was going uphill, I know hard to believe, but i did get a ticket.  I told the officer I did some work on the truck, and swapped in a five speed transmission.

the arresting officer suggested I take the truck to a speedometer service shop, and get the speedometer tested.  This was before GPS.

I did that, and when we were in court, before the judge called my name, the officer asked if I went to the speedometer shop.  I told him I did. he looked at the slip of paper the shop gave me, and then handed it back. 

When the judge called my name, the officer asked to "address the court".  The judge granted the officer that permission. 

The officer explained my speedometer was off, reading too slow.  The officer asked the judge to dismiss the ticket.  The judge then asked me if I had a problem with that.  I replied "no" and walked out of the courtroom, with no penalties.

 

Wish my Datsun would do 15 seconds between mileposts.

[mrbigtanker]

That was a cool cop.You got a dismissal.And it is always worth to fight a ticket in court,if the cop does not show up you 95% will get dismissed.

[oldskoolvws]

Beat a cop once in court by using tactics. He ran down thee whole scenario, stated he remembered it clearly. I asked him in front of the judge "how many people were in my vehicle? He stated I was solo; including myself, there were 3. Judge dropped it based on his failure to recollect. The one and only time I got lucky in court.

[skyblue]

this is a cool wheel/tire calculator that lets you compare two wheel/tires sizes to each other. if it helps.

 

http://www.rimsntires.com/specs.jsp

[alabama_lowlife]

I checked it today with a GPS speed app. I compared the app to the speedo in my wife's and it was pretty close. On the 521 speedo I was showing 60 and the app showed about 52....I'd pass me too lol