Can I go faster with big wheels??

[jeffrey rehbine]

Need some help deciding about wheels. . .
I have a 65 Chevy c-10 with the factory 4spd w/crawler. It has 15" rims and little dry-rotted P205 bias-ply tires on it right now. Although I can get it going @70+ mph on the hwy, the 230 motor is pretty much in hyperdrive rpms. I am trying to locate some stock 16" rims because, not only will they look better, but I'm thinking larger tires and rims will lower my hwy rpms and give me a little better gas milage (rather than going to all the trouble of messing w/my rear end)
My questions are:

1. Will my rpms be much lower with a larger diameter tire?

2. Will my 1/2 ton pickup handle a larger rim/tire size on its current suspension?
3. If I need to lift my pickup a little, would replacing the 1/2ton coils with 3/4ton springs make any significant diff?? :7

 

[57heaven]

RE: Can I go faster ...??

howziit Jeffry!

log on to www.smokemup.com

with their formulae, you can estimate rpm, with any change to tire diameter.

 

[jeffrey rehbine]

RE: Can I go faster ...??

> howziit Jeffry!
>
>log on to www.smokemup.com
>
>with their formulae, you can estimate rpm, with any change
>to tire diameter.
Thanks 57 Heaven! I checked out smokemup.com and found out that my idea will work great. When I replace my P205 tires with P265/70 my rpms will actually be 500 less @ 60 mph!! Not only that, my top speed will now go from around 80 mph to 90+ mph (not that I plan to cruise that fast). This should make a signif diff in my milage too (until I drop in my bros '68 327 vette engine).

So bigger really is better! :7

 

[57heaven]

RE: Can I go faster ...??

howziit Jeffrey!

you're welcome!

yep, taller is better in your case. you can get slightly less rpm, if you choose -78 series tires, instead of -70 series.

BTW, my 3.9:1 gearing dropped to 3.50:1, when i factored in my 29" tires, dropping rpm from 3000 to 2700 rpm at 60mph.