50mph w/33"=what?

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In a van, down by the river
33" tires on and traveling 50, (according to speedo). So how fast am I really going? Anyone know of a conversion table of some sort?

My guess is it is about 65mph. but I would like to know for sure.
 
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one trick that you could do is :- using a bicycle speedo you can input tyre size, connect to your vehicle, and wha-la you have a digital speedo with the correct speed/tyre ratio
 
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It's more like 55-58 mph depending on exact tire diameter. If you gave me the rpm then I could figure it out exactly.
 
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Actual speed

Actual speed = speed showing by the speedometer multiplied by the new tire diameter divided by stock tire diameter
You have to use same units for diameter, ie inches or cms
So in your case you have to convert the stock tire diameter to inches.
Vic
 
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Actual speed = speed showing by the speedometer multiplied by the new tire diameter divided by stock tire diameter
You have to use same units for diameter, ie inches or cms
So in your case you have to convert the stock tire diameter to inches.
Vic

...if the only thing that changed was the tire size.
 
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Get a friend in a regular vehicle to pace you and use your cellphone. Thats how I did mine back in the day. Then printed up some #'s and taped them where they should be. It was ghetto, but worked 100% and especially good when broke in college.
 
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Actual speed = speed showing by the speedometer multiplied by the new tire diameter divided by stock tire diameter
You have to use same units for diameter, ie inches or cms
So in your case you have to convert the stock tire diameter to inches.
Vic

Exactly. So 50 mph X (33"/29") = 56.8 mph true speed.

In all reality it's really the circumference that matters, BUT the pi s (22/7) cancel each other out.

That's IF your 33's are a true 33 inchs and IF 29's were stock.

The GPS idea is also good and pacing yourself with another rig is a good idea as well. :cheers:
 
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In a van, down by the river
Great input all...

Felt like I was going much faster, (also was hoping I was going faster). But after review of all the input here, I think I was imagining that.

So with speedo at 50 I am doing 55-60, (rough numbers). Close enough for me.

Thanks all.
 
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Find a stretch of freeway with a good set of mile markers (at least 5 to 10 consecutive markers) and watch the odometer starting at the first catch the number, catch it at the next, so on so forth, for every tenth of a mile that you loose along that stretch is 10% that the odometer is off by. I found with 33's I was 10-15% off so 50 was actually 55-58 or so. With 36" tires it's 20% so 50 is actually 60

That trick has always worked for keeping me out of speeding tickets after I first learned it.
 
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Find a stretch of freeway with a good set of mile markers (at least 5 to 10 consecutive markers) and watch the odometer starting at the first catch the number, catch it at the next, so on so forth, for every tenth of a mile that you loose along that stretch is 10% that the odometer is off by. I found with 33's I was 10-15% off so 50 was actually 55-58 or so. With 36" tires it's 20% so 50 is actually 60

That trick has always worked for keeping me out of speeding tickets after I first learned it.

That's not a very accurate way to judge your speed. The government put those signs out......
Just get a tachometer and calculate it out and you will know for sure.

I think was kept you out of speeding tickets was driving a 40 series......
 
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My speedo reads 5 mph at full stop, 30 mph at 25 mph, and 60 mph when I'm actually going 65. What's MY problem?
 
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I just drive with traffic and try to never go over 3000 RPMs on the tach on the hiway

If a cop pulls me over I always planned on saying, "What?! How fast? Look at this POS, how is that even possible?" That was 15 years ago... still haven't had the chance. :flipoff2:
 

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