Is anyones tire rev spot on? I recently purchased Nitto 555. My rear tires are 285/40/18, so according to the website the rev per mile is 770. Checking my car's speedometer against the GPS speed, around 60 and above the car speedometer reads about 5 MPH slower. I kept uping the revs per mile with my tuner. I am at 790 revs. per mile and it still reads 2 MPH slower than what my GPS registers.
You'll rarely find the tuner rev/mile bang on, even stock my actual is 98km/h with an indicated of 100km/h. My trucks, my srt8 was the worst, my settings to get the speedometer less than 1% error.
Run some long flat sections of highway, keep adjusting until you're bang on, get down to the tenths, as in 59.5mph for example, don't worry about the entered data #'s.
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2010 grabber blue GT, HID's, nav, glass roof, keyless entry, remote start, auto, condom-like clear plastic coating rock protection, SCT tune, what to do for mods..........intake, x-pipe, cat-back, TB maybe, some 255/40-19 sp2's for the summer........
While it's a British site, it still gives mph for different size tires.
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'05 Sonic Blue GT w/ '07 V8 engine, 5-sp, IUP, Beige leather interior, nothing else -
just the way I wanted it. (1 of 113)
OK, so I've added a few things to it. Check my Profile - too many to list here.
There is no formula you can find to be accurate as flat roads and a gps. A stamped size can vary 1/2" between manufacturer's different casing, tread depth. Use the gps, I target say 99km/h indicated, and 99.5km/h actual. The diablo tuner let me adjust sizes very fine with xxx/xx-xx input, but my sct in the truck (now programmed for my gt) was revolutions, not as fine tunable but still ok. Haven't done the sizing yet, going to plug in my dashhawk and do it, it has a digital speedometer that reads the same as the dash, I'll program with exact #'s then.
Even if you end wup with something totally wierd for rev's/mile, it doesn't matter as long as it's close. Best to always check as the tire wears too, rev's/mile increase.
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2010 grabber blue GT, HID's, nav, glass roof, keyless entry, remote start, auto, condom-like clear plastic coating rock protection, SCT tune, what to do for mods..........intake, x-pipe, cat-back, TB maybe, some 255/40-19 sp2's for the summer........
My Nitto 295/45-18 according to Nitto should be 734 rev/mile but I use 711 and it's almost spot on. Stock tires look like about 771 for 18's. I found that if I make 50 rev/mile change at time I can tell if I'm getting in the ball park. 1 or 2 rev/mile change you won't notice make a larger change.
Just remember if the tire is taller than stock number goes down.
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06 GT Premium in Legend Lime, Konig Beyonds, Hurst, JBA, Steeda stuff, MAC CAI, Sniper tune, LT's, H pipe w/Pypes cats, VIS Racing CF heat extractor hood, Tokico D-Specs, Ingalls Engineering, Silver Horse Racing, LLR #0174
Tire revs. per mile 
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