The Stovebolt Site Forums The Shop Area General Truck Talk Highway Speeds

I expect to have my 'new'(to me) 66 1/2 ton on the road by this weekend. With this I'll be able to find out part of my question as to how much will the engine wrap up at 60mph. I may be jumping the gun here but IF it whines too much, would putting oversize tires (just a little taller) be a viable solution? It currently has LT235/75R15 tires. I realize this would make the speedo inaccurate, but that doesn't bother me. Will bigger tires make it unstable at 60mph or really mess up the handling? Thanks in advance.

Rance

My 64 with a 230, three speed manual, and 4:11 gears whines a little on the highway. I have small 15 inch rims with low pro tires (sorry I just got home from work and don't want to check exactly what my tires are ). It humms at 60, my speedo is way off but that doesn't bother me. I only worry about overheating when I drive on the highway for a long time. One of my rear tires went soft so I took them off for a week and put some 16inch "whatever's" on it, the engine didn't rev as high on the highway and it felt just as stable at those speeds. Sorry, can't help you with the handling part. Good Luck.

don't know about "viable solutions" Rance, but the larger the diameter of the tires, the lower the revs at a given speed, so it'll save a few RPM, tho not a lot - taller rear gears is what'll be the real solution

I put 700R15 Yokohamas on the 58 and the lower RPM was noticeable - looks like a truck now, steers easier too, and the narrower tread is actually better on wet roads, no stability problems w/ higher or narrower tires unless you've got suspension or steering issues outstanding

Bill

Try to go with rear tires that have a diameter close to 30". Like the guy above I have 7.00-15 bias ply tires and the diameter is about 29.5" and they work well. Only other option is costly ring gear and pinion change or a late model rear end swap.

RANCE, go to www.randysringandpinion.com and www.1010tires.com and use their calculators to figure tire height and rpms. you can play around with calculators til you get the combo that will work for you. RON

I have a 64 230/3spd/3.73, been driving it 70 mph on the highway. I checked my speedo/odo w/a GPS. I have 225/75/15s all around. I was worried at first it would be too low geared but the six seems just fine, although it don't like going any faster than 75. Brian

When I was running the 230 in my 64, I had 31 x 10.5 x 15 tires on all four corners and ran 65+ for 20 miles every day. They also filled them huge wheel openings up better,
Scott

My '66 C-10 has 225/75/15 radials on it, and rides well at 60-65 on the highway. I don't like the feel of this truck at speeds over 65.

posted 13 July, 2005 14:37
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Where's ftyler lurking at? Hmn...

-W

Thanks all for your input into this.

Rance

PS: Woogeroo, Every time I see one of your many helpful posts, it makes me sing at least the first line of "Back Off Boogaloo" by the Beatles. I'm sure you have a great story of how you came up with "Woogeroo".

Rance

I'm running 235/85 16's on my 69. I was told that this is the tallest combination. Handling is fine and the speedo is about 10 mph off at 65. Redcoat

Here I is Woog!

Rance,

Everyone else has covered this well. I have a '66 stepside (that hasn't been driven in 6+ months, sadly enough) and I once had a 230/3 speed/3.73 gear combo. With my 235/70R15s its top cruising speed on the interstate was 65 mph.

So I built a 292 and kept the same wheels/tires and rear end gearing, but added a 4 speed manual stick tranny, with 4th gear being overdrive. Now the truck turns about 1900 rpms at 60. And when I want to jump on the interstate, I have no trouble doing extended trips at 80 mph with the fast lane traffic, as the overdrive keeps the rpms at only 2600.

My advice would be to drop in a 4 or 5 speed overdrive and be done with it. The "taller tires" solution is not going to take your truck from being a "high rpm/low speed" beast to an easy interstate cruiser.

-ftyler

ftyler's truck has a nice sound to it also... vRoom.

ftyler, you betta drive that thing or it'll fall apart. I can volunteer to take it on a speed run.. ha ha ha.

-W