Wide vs. Narrow Driven Wheels

[Zeero]

I'm a complete noob at this. I just want to get the stupid questions answered before I show up at WOS next year.

I understand that narrow tires get better results on the salt, but does that also apply to the driven wheels?? I plan to run for the 130 club in a daily driver Nissan 350Z and narrow tires on the front make sense, but seems like I would want as much rubber down on the driven wheels as possible to scratch up to the speed needed in a measured mile. I can't imagine that narrow tires will make that work, but I've never done this before.

[Glen]

Zeero this will bring a lot of different answers and opinions. Most high speed records are on narrow special Bonneville racing tires rated for those speeds. Some run a wider Daytona tire and swear by them. They are also blamed for causing spins. You are planning on running in the 130 mph club and tires rated for those speeds are listed in the SCTA rule book. As Bonneville is different then anything you have run on you will be restricted to a drivers license test 125 to 150 mph. The rules for the 130 club are posted on the USFRA web site. Good luck on your adventure to salt flat racing and welcome to the forum.

[Zeero]

Thanks, Glen.

Yes, I understand that I have to absorb all the rules and abide by them. I'm pretty anal compulsive about that. I won't run any tire that is not at least a "W" rating, but I don't want to buy saltflats tires all around if something else on the driven wheels will help me get up to speed in a mile. Seems to me that the 130 or the 150 club is a lot harder than unlimited go-fast runs on the long courses. If somebody made a "W" rated snowtire, that is what I would use on the driven wheels, but that ain't in the cards.

I'm looking for salt drivers who can advise me whether narrow or wide DRIVEN wheels (in their expeience) can make a difference in terminal velocity over a one-mile measured course.

I am SO pumped to do this next year. I wanted to do Speedweek this year, but life got in the way. I think World of Speed is in my bucket list for 2012.

[Dr Goggles]

Seems to me that the 130 or the 150 club is a lot harder than unlimited go-fast runs on the long courses. If somebody made a "W" rated snowtire, that is what I would use on the driven wheels, but that ain't in the cards.

I expect there's a few people who will dispute the difficulty of the 130 club.

Tires that "damage" the course are disallowed, your road tires will do just fine as long as they havwe the right rating .....you could do worse than get someone other than a grunt to balance the wheels and tires.

I'm looking for salt drivers who can advise me whether narrow or wide DRIVEN wheels (in their expeience) can make a difference in terminal velocity over a one-mile measured course.

I am SO pumped to do this next year. I wanted to do Speedweek this year, but life got in the way. I think World of Speed is in my bucket list for 2012.

The advice you will get here about tire width will trend to narrow, but there will be some persistant advocates for the wider rubber. Likely you're under 400hp, with little pedalling you shouldn't have any trouble as long as you do your sums right and have the right final drive to reach the speed you're after.

You are shooting for 130, not outright speed, there are calculators here that will help you get a rough idea of how you will get there but with so many variables the results may be gibberish.

1./ Calculate your rear tire circumference.
2./ Calculate top gear ratio( is it 1:1 or an O.D box)
3./ Calculate the distance the car travels for each revolution of the motor( you'll need the reciprocal of your diff ratio)

Now, the number of revs per minute will tell you how far the car moves in a minute, multiply by 60 will give you an hour... When you do the little sum to work out the distance time relationship you can calculate mph per 1000rpm's


I could have given you a formula there , but I would have expressed it in metric measurements (like um because it's waaaaaay easier) and converted back to MPH.......


I'm sure you can work it out.

Bottom line is tire slip ( in the relationship between V and rpm)and terminal vel.  aren't issues that are going to trouble you too much in the 130 club...Tire slip will increase as you go faster due to the increased resistance to your forward movement, and that's where ballast becomes an issue.

Welcome to the game.

[bvillercr]

Not many run wide tires, but there are many more spins on narrow tires than wide ones.   

[JamesJ]

I'm looking for salt drivers who can advise me whether narrow or wide DRIVEN wheels (in their expeience) can make a difference in terminal velocity over a one-mile measured course.

A wider tire will increase your cars drag.  A narrower tire will put the power down on a smaller track and not float as much as a wider tire, think rice farmers and mud racers.  Will this make much of a difference in the 130, most likely not.  But a narrow tire will result in a higher terminal velocity.  That just what I think...

[jl222]

 
  You should be able to get up to 130 mph on narrow tires, but i'm not sure of course length for 130,and you
woun't have to listen about wide tires not working.
  280mph at the 21/4 and 294 in 1st timed mile for us, with wide tires on parts wash in a passenger car.

               JL222

               
 

[SaltRat]

My experience: 150 club is a piece of cake, the 130 is much more difficult.

150 is a two mile run up to the timing lights, 130 is only a mile.  Most cars are traction limited on the salt (my car would only hook up in fifth gear) making acceleration "interesting."

Have fun!

[Stan Back]

If your Z has a 5- or 6-speed, you may already have the best available ratio.  Top gear probably is too high and hard to pull to 130 in a mile. Get an Isky dream wheel and let it do the math.

[836dstr]

Not many run wide tires, but there are many more spins on narrow tires than wide ones.   

You guys that sucessfully run wider tires have your "Aero/Chassis" packages sorted out. That's to your credit.

It's kind of a chicken & egg question. There are more spins on narrow tires because many more people run them. Tires are only one of the many causes for spins, and probably not one of the major ones.
Tom

[RayTheRat]

I can tell you that there's enough grip on narrow Goodyear Front Runners to break the pinion yoke and twist an "unbreakable" driveshaft into a pretzel shape (sorta) at 137 going into 4th (OD) with roughly 500 hp:
http://www.chevyasylum.com/85monte/85monte28.html

One reason for smaller width tires (so I've been told...I'm not an "old salt" by any means) is to put maximum weight on a small contact patch.  I've also been told that, as a way of illustrating this point, an average-sized woman wearing spike heels places as many pounds per square inch (on a small area) as an elephant's foot does (over a large area.)  I haven't personally tested this. 

The rolling resistance thing is another reason I've heard. 

Your mileage may vary, but if your current tires are legal for the 130 club at the moment, then it otta be able to make that speed in 4th.  (My son owns a 350Z and I think that's the gear that would work...but I've only driven it once.)

[Cranky1]

Ray, did you check your drive shaft for true after you installed it? I've seen them look like yours before because of whip. I've never ran top speed on an open track but I've spent a lot of time on the 1/4 mile and seen more than my fair share of broken and bent parts lol

[Milwaukee Midget]

Zeero - welcome aboard.

When it comes to overthinking, second guessing and backtracking, I'm a professional.

I think you're overthinking this one.

The 130 club is as close to a "street stock" class as land speed racing gets.  Key is to keep it affordable and fun.

In the case of the 350 Z, I'd be pretty confident that the stock tires would be your best choice as far a balance between traction and safety, provided they are H, W, V, or Z rated, and are in good shape.  That car should remain pretty stable in that speed range.

The big upside is that you've already got them. 

Keep in mind - you're only going one mile in a daily driver.  I'd use the stockers, probably up the air pressure a tad, and just stay very aware of what the car is telling you.  I'd think you should be able to coax the Nissan into the 130 club without a lot of overthinking, and if you don't, it'll probably be pretty darned close, and a heck of a lot of fun.

See you in September.

Chris

[fastman614]

For calculating RPMs to speeds, I don't use a specific formula.... I use a bunch of arithmetic equations and then use eithet the products or quotients as numbers in successive equations.

Like so: Example is  a 26" diameter tire....

26 / 12 = 2.1666 (feet)

2.1666 X 3.1416 = 6.8047 (feet in circumference)

Okay, one mile equals 5280 feet.

5280 / 6.8047 = 775.9336 (revolutions per mile - NOT per minute)

Desired top speed is 130 MPH.

130 / 60 = 2.1666 (miles per minute)

Now:

775.9336 X 2.1666 = 1681.1378 (Wheel Revolutions at 130 MPH)

Finally- your rear axle ratio (Example 4.11-1)

1681.1378 X 4.11 = 6909.476 Driveshaft RPM - also engine rpm with a direct drive top gear (and assuming NO tire slip)

If your rear axle ratio is, say, 3.00 - 1, well you will need to use other than top gear with the RPMs I am pretty sure you would want to be revving your 350Z engine up to.... and you will need to know the various transmission gear ratios so that you would take, say, fourth gear at hypothetically 1.2 - 1 and either multiply your rear axle ratio by that when you calculate or simply multiply the end product by that ... either way will work... but by doing it at the end, you can also easily multiply by the third gear ratio... or the second gear ratio... heck... you can use it to see how fast you will be at the top of each gear and work out RPM drops as you shift through the gears too....