I switched from 28" tall tire with 4.10 gear to 3.42 with 25.7" tall tire. My car feels rather sluggish now. Would it be a no no to install 4.10 with my 315/35/17 rear tires? What would my RPM be in the 1/4 mile with this combo?

Thanks,
Rob

It all depends how fast you want to go. The same tire on our street toy measures 25.5" and that comes to 5943RPM at 110 MPH or 5402RPM at 100MPH with no slippage and 4.1 gears. Or over 10,000RPM at 200MPH http://www.nastyz28.com/ubb/wink.gif

You can look here to find what you need:
http://www.prestage.com/Car+Math/Gear+Ratios+and+Tire+Sizes+/Calculate+RPM/default.aspx

Thanks for the link.

Rob

I went to the RPM calc link and have no idea what to put in for the trans ratio. Is that a 1 for turbo 350/400 and .7 something for an overdrive??

Hope this lines up to be usefull...


AUTOMATIC:

POWERGLIDE - 1.82 - 1.00
1.76 - 1.00
TURBO 4L60 - 3.06 - 1.62 - 1.00 - 0.70
TURBO 4L60E - 3.06 - 1.62 - 1.00 - 0.70
TURBO 4L80 - 2.48 - 1.48 - 1.00 - 0.75
TURBO 4L80E - 2.48 - 1.48 - 1.00 - 0.75
TURBO 350 - 2.52 - 1.52 - 1.00
TURBO 400 - 2.48 - 1.48 - 1.00
TURBO 200-R4 - 2.74 - 1.57 - 1.00 - 0.67
TURBO 700-R4 - 3.06 - 1.62 - 1.00 - 0.70

MANUAL:

BORG WARNER T10- 2.23 - 1.76 - 1.30 - 1.00
2.43 - 1.64 - 1.24 - 1.00
2.64 - 1.76 - 1.35 - 1.00
2.64 - 1.64 - 1.24 - 1.00
2.88 - 1.76 - 1.35 - 1.00
2.88 - 1.91 - 1.35 - 1.00
3.42 - 2.28 - 1.46 - 1.00
3.44 - 2.28 - 1.46 - 1.00

BORG WARNER T5 - 2.95 - 1.94 - 1.34 - 1.00 - 0.63 (TBI)
2.75 - 1.94 - 1.34 - 1.00 - 0.74 (TPI)

BORG WARNER T56- 2.66 - 1.78 - 1.30 - 1.00 - 0.74 - 0.50
2.97 - 1.94 - 1.35 - 1.00 - 0.84 - 0.62
3.36 - 2.07 - 1.35 - 1.00 - 0.84 - 0.62

MUNCIE M20 - 2.56 - 1.91 - 1.48 - 1.00
2.52 - 1.88 - 1.46 - 1.00

MUNCIE M21 - 2.20 - 1.64 - 1.28 - 1.00

MUNCIE M22 - 2.20 - 1.64 - 1.28 - 1.00

SAGINAW (4spd.)- 3.11 - 2.20 - 1.47 - 1.00
2.85 - 2.02 - 1.35 - 1.00
2.54 - 1.80 - 1.32 - 1.00
2.54 - 1.80 - 1.44 - 1.00

ZF6 3.07 - 1.80 - 1.43 - 1.00 - 0.71 - 0.59