so im crossing through the traps just shifting into 4th. ive always heard to get the best E/T, you need to be crossing in 4th at about 200rpm or so over power peak. to do this i would either need to get shorter gears (not an option... too $$) or smaller tires. currently im running the stock 15x5.5" steel wheels with 195/65R15s. i believe tire diameter, non-mounted, is 24.5"
is it possible to reduce tire diameter so much on these cars to go through the traps around 5500-6000rpms in 4th? can 13" wheels fit without any problems, or is that too small? any recommendations would be appreciated
1998 Chevrolet Camaro Z28/1LE
- LS1 6speed, 3.42s
ported 5.3 heads, comp 224/228 cam, boltons
(410rwhp/390rwtq)
I don't think you can go any smaller than 14". 14s fit fine--I have a set of 14" steelies that I run in the winter. I think 13s would be too small though.
Just get some shorter tires, not smaller rims. If you're using 195/65/15s now, try something like a 195/50/15. That should be about 2.3" shorter that the tire you're using. Or for a slightly wider tire for more grip try a 205/50/15, that is about 1.9" shorter.
Hope that helps.
- 93 mph in the 1/8 mile
Member of J-Body Of Michigan.
I like smaller tires. I currently run 205 50 14, The next thing im lookin at is wider, cuz im still spinning a little, but with 2.0's 60' im not complaining, and im running low tire pressure, thats the secret.
Im out
-Ben
Best times of 2005
60' - 2.013 (5/28/05)
330' - 6.081 (5/15/05)
1/8 - 9.476 (5/15/05)
M.P.H.- 72.91 (5/15/05)
1000' - 12.506 (4/20/05)
1/4 - 15.018 (4/20/05)
M.P.H.- 90.47 (4/20/05)
1.99 60' here we come
Ben Wenzel Jr wrote:
I like smaller tires. I currently run 205 50 14, The next thing im lookin at is wider, cuz im still spinning a little, but with 2.0's 60' im not complaining, and im running low tire pressure, thats the secret.
Im out
-Ben
any idea on the tire diameter of that size? and in what gear at what rpm do you cross the traps?
1998 Chevrolet Camaro Z28/1LE
- LS1 6speed, 3.42s
ported 5.3 heads, comp 224/228 cam, boltons
(410rwhp/390rwtq)
There is a simple formula for wheel DIA (Example 205 50 14)
205mm/25.4mm=8.0708
now 50 is in percent of sidewall so
8.0708 * .50 = 4.0354 (times 2 for top and bottom) = 8.0708
now add the rim size
8.0708 + 14" = 22.07" is the DIA of this rim and tire combo
(Example 195 70 14) Factory size (I Think)
195 / 25.4 = 7.6771
7.6771 * .70 = 5.37401
ANS * 2 = 10.74803
10.74803 + 14 = (24.748 Factory Size)
in conclusion i run about 2.75" smaller than factory. My Shift points are 1-2 about 60', 2-3 about 330', 3-4 about 660', and run er out to about 5400 in the quarter mile, and have my shift light set at 6100
Im Out
-Ben
Best times of 2005
60' - 2.013 (5/28/05)
330' - 6.081 (5/15/05)
1/8 - 9.476 (5/15/05)
M.P.H.- 72.91 (5/15/05)
1000' - 12.506 (4/20/05)
1/4 - 15.018 (4/20/05)
M.P.H.- 90.47 (4/20/05)
1.99 60' here we come
Here's a shorter formula: (SW X AR / 1270) + RD=Tire Diameter
SW= Section Width
AR= Aspect Ratio
RD= Rim Diameter
Example: the diameter for a 195/65R15(the stock 15s)
(195 X 65 / 1270)+15=
9.9803+15=
24.98
a 205/50R15 would have 23.07" dia. or 1.91" shorter tire.
To figure the new EFFECTIVE GEAR RATIO : divide the OLD tire dia by the NEW tire dia and then multiply the sum by you gear ratio.
Example: I have the stock 15s with a gear ratio of 3.43. If I switch to the 205/50R15s this is what I have:
24.98/23.07*3.43=1.0828*3.43=3.714004
or essentially a 3.71gear ratio, which is actually a significant jump. Also note that that tire will fit a 5.5" wide rim. Jeg's carries the BF Goodrich G-Force Drag T/A in this size for $115.99.
