My 67 is mini tubbed (back to the frame) and I currently have 13 inches between the quarter panel lip and the inner tub. I will either cut the lip out or fold it in to gain a little more room. Should get me another half inch? For street driving I have on bfg's radial t/a's 265/60/r15 but with a fresh 500+hp BBC I will need a lot more grip to take it to the track.

Here's what im looking at
P275/50/r15(26/11.5/15) Local speed shop has these and with no wheel i mesuerd 10.5 (is it 11.5 on a 10 inch wheel?)
P275/60/r15(28/11.5/15) a little taller=more gear?
P295/65/r15(30/12.5/15)
P315/60/r15(30/13.5/15)anybody using these on a 10 inch rim? what is the real with? <<these would be a very tight fit to say the least.
Also should I go 8 or 10 inch rim?(295 have to be on a 10?)

The car has a t400/3000 stall 9.5 converter/3.55 rear end gears.
These tires will be mostly for the track/ill keep the bfg's for daily driving in
the summer.
Where will i get the best gain's? shorter tire due to my hiway friendly gears or widdest possible to put the power to the pavement?:confused:

If you have that much room then you need to know what height you are going to use with your gear ratio.
325/50-15, 28" tall
315/60-15, 30" tall

With 13" of room you can run either tire now with a 10" rim.

Dave

That's part of what I dont get...At a quartermile track with 3.55 gear would I be better off with a taller or shorter tire????
also arnt the 315's 13.5 inches wide on a 10 inch rim? I'm not sure how you mean I can get them in a 13 inch hole:clonk:
This is confusing
Paul

With a 3.55 gear you probably want the shorter tire. The 325/50-15 has a section width of 13.1" wide. You mentioned you now have 13" to play with, it should be close.

Dave

the 275/50/15 can look small on a 10" wheel depending on brand...(they rate them the same but they're full of crap)

275/60/15 look like complete crap on a 10" wheel

I bet depending on brand you can get a 325/50 that fits and looks nice

sorry..should have said M/T drag radials...
I should be able to squeze 13.1 in there no problem after I cut open the quarter wells

My 67 is mini tubbed...
Here's what im looking at
P275/50/r15(26/11.5/15) Local speed shop has these and with no wheel i mesuerd 10.5 (is it 11.5 on a 10 inch wheel?)
P275/60/r15(28/11.5/15) a little taller=more gear?
P295/65/r15(30/12.5/15)
P315/60/r15(30/13.5/15)anybody using these on a 10 inch rim? what is the real with? <<these would be a very tight fit to say the least.
Also should I go 8 or 10 inch rim?(295 have to be on a 10?)


Not sure about the wider tires, but the 295 should be fine on an 8" rim. I used to run a 295/50-15 on 15X8 wheels on my '66. Those obviously have a shorter sidewall, but the tire manufacturer's tech info indicated "recommended" range was 8" - 10"...

10" wheel MIGHT have clearance issues with the lower shock mount.

I am no expert, but the shortest tire you mentioned, 275/50-15 is almost 26" tall

This tire at 120 MPH ( with your 3.55 gears), means you'll be spinning the engine 5550 RPM ( @ 120 MPH), that not spinning too fast, even for a Big Block... Whats that equate to, about 11.20 ETs???

At 130 mph, thats about 6000 rpm... Thats about 10.40 ET range???

So, do you think your car will go that fast? (130 MPH in the 1/4 mile)? I think you want to be close to max HP at the finish line, right? Thats probably 6000-6500 in a mild BB, so still too tall for ideal...

The taller tires will likely be even worse for top-end power at the drag strip...

I have heard taller tires don't spin as easily as short ones, but not sure how accurate that is... If it hooks, the smaller tire should accelerate quicker, and if it won't be over-rev'd at the finish line, better choice...

Thanks team...this gives me some things to think about.
I will go look at the lower shock mount after work.
Remeasure my wheel well again and look at more tires.
Sounds like smaller hight tires might be the way to go...
Is there a calculator to figure out the e/t mph to tire hight?
If anybody has anything else to add please do...
Who else makes a good drag radial?

M/T also now has a 295/55/15 dr thats 28" tall

:thumbsup:That sounds like the one...295/55/15
Sorry i meant M/T et street radial... but anyway looking like i found my tires.
Thanks Team!!!!!:hurray::yes::hurray::yes:

Paul:beers:

:pThanks team...this gives me some things to think about.
I will go look at the lower shock mount after work.
Remeasure my wheel well again and look at more tires.
On my '66, I had 295/50-15 on 15X8 rims... I custom ordered the rims with a little too much BS ( I was anticipating getting rear discs which would push the wheels out just a bit more, but ended up staying with the drums...

Anyway, the lower shock mount was pretty close to the wheel. if it was inside the wheel, it wouldn't have fit...

My tires rubbed slightly on the frame ( but not the inner wheel well)... the tires were short ( under 26" height), but the car was slammed...

http://www.chevelles.com/showroom/data/500/medium/scan00042.jpg

Mine had lots of clearance to the outside ( ~3/8") with the stock lip and trim in place... I did roll the inner lip back, not really gaining clearance, but keeping the sharp edge from cutting the tire...



Sounds like smaller hight tires might be the way to go...
Is there a calculator to figure out the e/t mph to tire hight?


I can't remember where I have seen a calculator... here's a breakdown of the equations:

tire height (inches) * Pi ( 3.1415...), thats the circumference (inches), circumference divided by 12, and its in feet...

5280 feet/mile divided by circumference (in feet) = Revs per mile (tire)...

Revs per mile * rearend ratio = engine Revs per mile ( assuming 1:1 top gear in transmission and neglecting convertor slippage)

At 60 MPH your revs per mile = revs per minute (because 1 mile every minute)...

26" tire example:
26in. * 3.14= 81.68 inches ft/rev (circumference)... 81.68/12= 6.807 ft per rev (circumference)

5280 ft per mile/6.807 ft/rev = 775.7 tire rev per mile

775.7 rev per mile * 3.55 gear ratio = 2753.7 engine rev per mile (assumes 1:1 top gear, not OverDrive transmission)...

2753.7 RPM @ 60 MPH doubled = 5507 RPM @ 120 MPH... Or about 46 RPM per each MPH...

Assumes top gear is 1:1 and neglects convertor slippage, etc

Okay, so I am bored tonight...



Someone posted a 1/8 mile to 1/4 mile conversion sheet on here a while back... every car is different, but it seems to be pretty good for a ballpark number...

Alot of great calculators here http://www.wallaceracing.com/Calculators.htm