Tires: Rotating weight vs radial construction

[Ed Wright]

Originally Posted by Eric Merryfield

On a non tire question......how do you block just the middle bulb?

Eric

I

Eric, I bought some thin, clear Lexan from Ace Hardware to make mine. One for each lane. Cut with the other side of the tree blocked, and a notch for my lane. Painted flat black from the stage lights down. Doesn't take a very wide strip to block two ambers from that distance. Narrower than a strip of electricial tape. Could just as easily just block the second amber.
Without moving my head around I can see both lanes stage, then nothing else until my third amber. If I could see my first amber, I would be red every time.

I had aluminum blinders before, which required getting my head in position after staging.
Since I pretty much always leave first, if the starter is fast my side of the tree sometimes started down by the time I got my head positioned. I'm old, so am kinda slow. With these

I see everything I want to see without moving around.

When I A-B-A tested same size (9" at the time) radials versus bias tires on my car, the radials were a solid 2/10ths and nearly three MPH. I had just started trying to race again. Not sure it was a bright thing to do. Anyway, Pete Peery told me they would be worth over a tenth. I kinda doubted it, he hasn't steered me wrong yet. They were the same size, same brand (Hoosier at the time) on identical wheels. All passes within an hour.
Had to adjust my lights. Started going red with the radials.

You mentioned tire weight. I have a pair of MT radials on the car. Also, on identical wheels, a pair of same size within 1/4" roll out Goodyears. They are 5 lbs per tire heavier than the MTs.
They hook just as hard, my lights are the same, but they are 4 hundredths slower at the 1/4 mile, 2 hundredths in 60'. Must be the effect of inertia due to the weight, right? Five lbs on a 31" radius has a bigger effect tha five lbs off a 15" wheel, or a crank shaft. Wouldn't that be right?

[ALMACK]

Ed:
So the Goodyear rears have a total of 10 lbs more rotational weight and slowed the car .04 sec. ?

Good info there.

Since I have a 4 cyl. car I am looking at going to a shorter tire and a taller gear in the lighter classes I run. I'll keep the 4.56 rear and 30" slicks for the heavier classes.
I am hoping to reduce my rotational weight. Every little .01 counts.

[Ed Wright]

Yes sir. I would think it would slow a faster car less, probably effect a slower car more?
I haven't owned a set of Hoosiers this size (13"x31") so don't know what they weigh.
I have found taller makes more difference than wider as far as hooking also. May not be the same for other cars or tires. Has been the case with everything I have had.

Edit: I would think the tire weight ET effect would also lessen with smaller diameter tires? Like 28" instead of my 31"?
You can tell I'm just an old Okie, not an engineer.

[ALMACK]

Well, I have ran enough passes on some M&H DOT Drag radials in the last 8 months to come to a conclusion.
The DRs runs the same as my Hoosier 30 inch tall slicks on my car, even tho the drag radials are considerably heavier.( my car runs mid 12's)

Right now, I am running 28 inch tall M&H dot drag radials that I bought in 2007 mounted on 17 x 8 wheels.

They hook just as good and run the same e.t. numbers as my Hoosier 30 inch slicks on 15 x 8 wheels.

So now I need to find out if NHRA will allow 275-60-15 DOT Drag Radials from M/T in Stock.
My old M&H tires will soon wear out and my slicks are used up.

[Duane Eiskant II]

on my mustang i run the moser bolt in 9 inch housing and have only ever run the radials on it. Tried the M/T radial when it first came out, also a few different sets of good years but always go right back to hoosier. I run the 94" circumference and the light weight version. Can still get over 100 runs with the cords hanging out. None of the radial tires i ever used rubbed anywhere.

[partsbob67]

m\t now makes 26" and 28"x9x15 radials. got a pair of the 28's on my car now. love them!!