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Title: Road Speed and Ratios Post by: Shane Noone on May 23, 2013, 21:12:04 pm Hey guys, Just looking for a rough idea based on others experience with known ratios.
If I say I run a 205/70/15 rear tyre but I am unsure of my 4th gear ratio ( close ratio ) and unsure of my Ring and Pinion ( most likely 4.125 or 3.875 ) but my road speed at 3500 RPM's in 4th gear is 55 mph ( on the speedometer driven by 145/80/15 front tyre ) then has anyone run close to this road speed in 4th with a 205/70/15, that knows their ratios's..????? Thanks Shane. Title: Re: Road Speed and Ratios Post by: adrian on May 23, 2013, 22:02:39 pm 4.125 and 1.21 gives you close to 55 mph, a 3.875 would be about 58mph. Its all pretty close though... and there are probably a ton of combos that will get you close to that mph
Title: Re: Road Speed and Ratios Post by: Shane Noone on May 23, 2013, 23:06:02 pm Ok, thanks. Yeah found a gear ratio calculator programme that I can plug my " knowns" into now to get some idea on my ratios :-)
Cheers. Title: Re: Road Speed and Ratios Post by: ALB on May 23, 2013, 23:54:05 pm You're speed is fast by about 4% (a 145/80 is approx 24" tall vs a 155R at about 25") so don't forget to factor that in.
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