Top speeds!

[jackjeckel757]

[/quote]

and your speedometer will be off.

yep, I have 245/60 R15s on the front and 275/60 R15s on the rear, great in cornering and gives a good ride too.
my speedometer reads faster than I'm actually going and gets worse the faster I go. I had my wife follow me in the Monte so I know 35 on the speedo = about 27 in reality, on the highway it says I'm doing 100 when I'm only going about 80.
As for the take off and top speed, I haven't driven it with the stock tire size so I don't know if there is a difference, but I do know that my truck takes off fairly quick for a 305 and will hold 90 all day long on the highway, or till it runs out of gas...

[1979C20]

Well, my speedo, when it worked, always showed 5mph faster than I was actually going. So, will my accelaratio be faster but my top speed lower? Ive already noticed that my rpm-speed ration is different. Before, 2000rpms was 45mph. now 2000rpms is about 42, all according to my gps speedo. So I guess my gas mileage is going to go south now.

[Lt.Del]

So I guess my gas mileage is going to go south now.

that all depends on where you drive.  Do a lot of interstate driving, yes.  Do a lot of city driving, no.

I like a higher gear number (or equivalent to a smaller wheel/tire diameter) if I do a lot of city driving---quicker take off and you dont have to keep your foot in the accelerator, as compared to a tall gear (or larger diamter tire) and doing city driving where you'd have to keep your foot in the accelerator to get going.  

Each stop light, and you have to accelerate so much more to get her going with a taller gear (smaller number).  

[Irish_Alley]

With only that much difference I don't see that big of a difference and for every 5mph it will be .09 MPH difference. Lets say you have 3.23 ratio you will have a 3.23 with the 65s

[drag80]

and actually pretty low for a race deal...

I didn't want average person reading this and thinking thier stock set up should be cruising aroudn 6100.  heck, throw a Rick Hendricks 358cid engine in there and tach her around 9800 for 500 miles, no biggie.

sorry, don't rev your engine this high if it is stock

[1979C20]

Okay, so explain this on, all might internet peoples. (: haha. So, yesterday, 2000rpm equalled 42mph. And today..... 2000rmp equalled 49mph..... Nothing has been changed, removed, added, etc. what would cause the difference?

[Irish_Alley]

Is this with the tire change?

[Lt.Del]

eyeglasses dirty?

what kind of transmission do you have, manual or auto---if auto, lock up converter?  Makes a difference.
If you have an auto without a lockup converter engaged, then the rpms will rise and decrease depending on your accelerator actions.   If you are accelerating, your rpms could be higher but lower speed.   

[1979C20]

This change in speed to rpm ratio is after the tire change. By that, I mean, after the tire change, one night with 265/70/16s 2000rpms equalled 42. And the next night with 265/70/16s 2000rpm equalled 49. Both of these speeds is measured by my gps speedometer.

[Lt.Del]

could be tread depth, air pressure.  I ask again, what kind of trans?

[1979C20]

Sorry, its in the first post. Sm465 manual 4spd. Granny lown

[Irish_Alley]

thinking maybe something to do with the speedo cable, gear or gauge. not sure, is it staying at 49mph @2k? or did it go back down maybe clutch slipping???

[slammed79]

I topped my 79 out at about 125-130 on the I10 a few years ago, she was redlined and I was scared but it was jolly good fun.