Kuk,
Yeah, I'd love to get a copy of that program!! I've got a shareware
type program called Shiftmaster or something if anyone wanted a copy.
I've also got a simple little Excel sheet setup to do speed and rpm
calcutions based upon tire size, trans ratios, vehicle speed or rpm,
rear end ratios, etc. I'd be glad to forward that also. The Excel
sheet is what I used to calculate rpm for 215/75/15-3.21 rear stock at
70 mph = 1999 rpm. 285/70/15-3.55 rear gives 1985 at same speed.
I love the look of your combo Kuk so maybe I need to wait until I drop
the truck before I start lookin' at tires. I agree the 295's would
look silly on the 8" rim. If I go to a 10" wheel I'd like to try and
fit 305/50's back there. I also thought the height of the 285/70's
was pretty tall but the 275/60's are shorter than the stock tires.
Again, maybe I should wait until spring when I drop it.
Below is what the Excel sheet calculates (hope this doesn't screw up
anyone's email)
Wheel Size = 15 in. Engine RPM in final ratio = 4400 RPM
Tire Width = 285 mm.
Aspect Ratio = 70% Vehicle Speed in Final Ratio=155.113MPH
Gear Ratio = 3.55
MPH = 70 mph Transmission Ratios
1st gear= 4.01
Tire Diameter = 30.7087 in. 2nd gear= 2.32
Section Width= 11.2205 in. 3rd gear= 1.4
Max Wheel Width= 10.0984 in. 4th gear= 1.0
Ideal Wheel Width= 8.97638 in. 5th gear= 0.73
Min. Wheel Width= 7.85433 in. 6th gear= 0
Circumference = 8.03951 ft. Shift RPM= 4600 RPM
FPM = 6160 fpm
Final Ratio = 2.5915 Vehicle Speed in Gear
1st gear= 29.5211 MPH
Engine RPM = 1985.65 RPM 2nd gear= 51.0256 MPH
3rd gear= 84.5568 MPH
4th gear= 118.379 MPH
5th gear= 162.164 MPH
6th gear= #DIV/0! MPH
______________________________ Reply Separator _________________________________
Subject: Re: Re[2]: shortening axle housing
True, too much, that is a 30.75 inch tall tire, compared to a 295/50/15 which
is 26.5 inches tall. I have a horsepower program I could send you that
calculates all tire sizes and tranny gear speeds with certain tires installed
if you want it, or I'll post it to the page for anyone to download, simple yet
extremely effective. I run 245/60/15 with a 3.91 gear ratio which gives me a
true 4.13 ratio on the ground. Your 3.55's would be reduced to around 3.00.
Kuk
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