I ran my 96LSC last summer and had terrible 60 foot times and weak end numbers too. I have 18x9.5 Y2k Cobra rims with 265/40 Bfg KDW tires. They don't stick that great but what really caught my attention was when I installed them, they weighed so much more than stockers. 60lbs vs. 45lbs for stock silver 10 spoke rims with mich. pilots. On the street I didn't notice a speed differance, just that big wheel feel thats normal. How much do they slow me down? BTW they look incredible, and now I'm so used to them the stockers look like temp spares to me.

maybe .10 of a second in the 1/4 mile.

Got any pics, that must look freakin great! Do you have mustang hubs, or did they come in the mark bolt pattern?

18" probably made your tires taller (literally, the height of the tire) which effectively raised your gearing. This makes your car slower.

15lb of extra weight on each wheel means a total of 60lb of unsprung weight added to your car!

Im not gonna talk out of my ass and throw you some number like the guy above me, but you can bet your ass your car with the new wheels is a dog compared to your old wheels.

Got any pics, that must look freakin great! Do you have mustang hubs, or did they come in the mark bolt pattern?
Sorry no pics to post. Its in the garage for winter and dirty, not exactly photo worthy. Winter came early this year. I intend to post many pics in the future as I do have some cool stuff. They're the Mark pattern and from what I have seen nobody seems to have them anymore. I chose the Y2K's to be alittle different from the normal Cobras. I think they look great also.

What I was told is the Mark VIII runs best on it's 16s and the snowflakes which are the lightest of the Mark VIII rims.

Correct me if I'm wrong....

18" probably made your tires taller (literally, the height of the tire) which effectively raised your gearing. This makes your car slower.

15lb of extra weight on each wheel means a total of 60lb of unsprung weight added to your car!

Im not gonna talk out of my ass and throw you some number like the guy above me, but you can bet your ass your car with the new wheels is a dog compared to your old wheels.
The tires are actually about 1/2 inch shorter than stock. Taller wheel, lower profile tire.

What I was told is the Mark VIII runs best on it's 16s and the snowflakes which are the lightest of the Mark VIII rims.

Correct me if I'm wrong....

I can't disagree.

I love the Y2Ks! I wish they still made them, cause id probably buy some. When you can,.....Get some pics man!

What'd the car run?

60' 2.562
1/8 10.174@73.83
1/4 15.421@93.88
Spinning thru 60' at least. With the traction control on it was worse, it switchedfrom tire to tire real stupid like.

Yeah, that 60 is horendous lol

Just wanted to see if this was yet another 14.6 stock Mark VIII :D

Yeah, that 60 is horendous lol

Just wanted to see if this was yet another 14.6 stock Mark VIII :D
I wish, If I practiced my launch, I think I could break 15.
Do have some basic mods. The reason I posted was to see if that kind of 60' and still a 15.4 shows potential for high 14s. Plus the wheel mass, how much drag are they?

I heard this a while back:

1/2 lbtires are about a 1 lb of extra rolling weight
1 Lb rims end up being 4lbs
1 Lb of driveline weight is like adding 30 Lbs to your car!

I know these are rough but it'll give you an idea...

I heard this a while back:

1/2 lbtires are about a 1 lb of extra rolling weight
1 Lb rims end up being 4lbs
1 Lb of driveline weight is like adding 30 Lbs to your car!

I know these are rough but it'll give you an idea...
At first that sounded high, but if the tire is 7lbs of it, and the rim is 8lbs of the xtra wieght. Thats 184lbs. Could be close. Thats a tenth at least. Any other good imput?

I wish, If I practiced my launch, I think I could break 15.
Do have some basic mods. The reason I posted was to see if that kind of 60' and still a 15.4 shows potential for high 14s. Plus the wheel mass, how much drag are they?

Generally, every tenth you shave off the 60' you shave 2 tenths off at the big end. So if you were to cut a 2.0 short time, you'd be lookin' at a 1 second reduction in your ET. I don't think you're gonna get that 2.0 short time with a stock converter and gears though.

Generally, every tenth you shave off the 60' you shave 2 tenths off at the big end. So if you were to cut a 2.0 short time, you'd be lookin' at a 1 second reduction in your ET. I don't think you're gonna get that 2.0 short time with a stock converter and gears though.

I agree, but a 2.2 is common for a stock but well tuned Mark. Yet many do only a 15.4. My 1st Mark for instance I hit a 2.3 yet a 15.5. So if I hit a 2.2 with this one, 14.8-14.9 should be possible. Thats what I'm trying to confirm to myself, that my mods, only being minor, are paying off. And my wheels, are part of the poor numbers.

Pulling this up from the past as I'm going to start to race it soon, well after my LSE breaks into the 14s. Throwing the stock wheels on may be the only thing I do before the first run and I'm looking for imput on what I can expect with just the wheel change. Gears and chip are next on the list, then shift kit and 255 fuel pump, pullies and better exhuast will probably follow, etc...

I've heard 1lb of wheel weight ends up being worth around 6lbs on the car. So 60*5 would be around 200, which should be worth about 3 tenths.

In your case I also blame the tire. A taller sidewall will hook better. If 15s would clear the brakes I would consider running them for that reason, since they won't I'm sticking to snowflakes.

My experiance was adding about 5lbs per wheel/tire on my ETC, and having it run the same 16.4 time. At the time I had shorter tires that effectively increased the final drive ratio from 3.71 to 4.22. The better gearing but higher weight seemed to cancel each other out. BTW both days the density altitude hung around 9000ft.

See if you can find a set of Snowflakes for racing. They are a lot lighter.

Maybe I'm wrong but the car was set up to run on 16s. Would that matter?

The 18's are slowing you down by about 2 tenths compared to the stock wheels. Why don't you throw the stock wheels/tires on there and see how it runs if you are so concerned about it.

This combo...
http://mark8.org/users/driller/pics/mini-100_1617.JPG
weighs in at 35lbs per wheel compared to 50lbs per wheel with the chrome 10 spokes and Nitto drag radials or Michelin Pilots.

Due to other mods during/after, it was difficult to ascertain a definite quantitative improvement in ET attributed solely to lighter rotating stock.

But believe in physics. It works everyday. ;)

do you just run those on the back, with 18's in the front too, or do you run 16's all around when you go to the track?

Oh BTW here are some figures on the rotational weight versus static weight conversion.






When converting rotational weight into static weight multiply times 8.

When converting back then just divide by 8.

Rotational weight affects a vehicle 8 times more then the same amount of weight just having to be lugged down the 1/4 mile (static weight).

Now this can never be perfectly accurate because it would have to take into account how far away from the point of rotation that the majority of the weight is, but it can be used as an accurate rule of thumb.

So, if we used 5 lbs difference per rim/tire as an example then it would be (5 x 4) x 8 = X

X = 160 pounds in this case.

Going off the old adage of 100 static lbs = .10 seconds in the 1/4, this would be a diff of .16 seconds with an average vehicle.

Now, the faster your vehicle is the less difference (proportionally) of ET that weight saving makes. This is why the 100=.10 rule works more accurately with 13-15 second cars, but not so much with 9-11 second cars.

Hope this helps anyone whom may be curious.

When converting rotational weight into static weight multiply times 8.

When converting back then just divide by 8.

Rotational weight affects a vehicle 8 times more then the same amount of weight just having to be lugged down the 1/4 mile (static weight).

Now this can never be perfectly accurate because it would have to take into account how far away from the point of rotation that the majority of the weight is, but it can be used as an accurate rule of thumb.

...

Now, the faster your vehicle is the less difference (proportionally) of ET that weight saving makes. This is why the 100=.10 rule works more accurately with 13-15 second cars, but not so much with 9-11 second cars.


In my case, 15 pounds x 2 = 30 pounds rotational weight
30 x 8 = 240 lbs static weight
240 / 100 = 0.24 seconds ET reduction

That would've been nice, but I doubt I actually achieved that. I suppose it might have been a tenth or so. But I figure my worn suspension is costing me in the launch so much it possibly negates the theoretical weight savings. :rolleyes:

In my case, 15 pounds x 2 = 30 pounds rotational weight
30 x 8 = 240 lbs static weight
240 / 100 = 0.24 seconds ET reduction

That would've been nice, but I doubt I actually achieved that. I suppose it might have been a tenth or so. But I figure my worn suspension is costing me in the launch so much it possibly negates the theoretical weight savings. :rolleyes:


You are right. There are other factors that come into play when swapping rim/tire combo's out. Stuff such as tire surface contact patch and traction come into play too, which though a car may net a little more MPH in the 1/4 due to faster acceleration it may not gain too much ET because of lack of traction off the launch. Analyzing time slips before and after the change will help a person diagnose what their achievement or problem was, and (better yet) why.

That was the case when I raced my Explorer last week. I had lighter rims and tires (with less contact surface) but I had to feather the launch soo much that I only ended up getting only .10 better when the weight diff was good for more than .25 seconds. In a situation, where the vehicle would be able to get sufficient traction in both the before and after scenario's, the rule of thumb stated above would be fairly accurate. :)

Thanks for the imput. I did have a traction problem besides the weight thing so I guess its one of those have to make the change to see. Sounds like .2 is the average of the opinions, throw .2 for traction should I get it and I have what I guess the car can do as is. Also the run was hot. Thats what makes it a challenge right, the what ifs and don't knows. I only ran that car that 1 time, who would of thought my LSEs 1st time out would be better, at least in the final 1/4. I will be solving these questions with definate answers soon enough, with a little help from my friends.

Thanks for the imput. I did have a traction problem besides the weight thing so I guess its one of those have to make the change to see. Sounds like .2 is the average of the opinions, throw .2 for traction should I get it and I have what I guess the car can do as is. Also the run was hot. Thats what makes it a challenge right, the what ifs and don't knows. I only ran that car that 1 time, who would of thought my LSEs 1st time out would be better, at least in the final 1/4. I will be solving these questions with definate answers soon enough, with a little help from my friends.



Oh yeah. It is all about being methodical. That is the only way a person figures out what the variables were that could have caused the differences in results. I should have took track temp readings, tire psi, how bad I was spinning, what rpms shifting, how much gas, so on so forth and wrote them on the back of the slips. Oh well, we can settle down and get methodical this next time. I dont have to let the LS cool for nearly as long as the Explorer does! :D

You know what. We should just datalog our runs on both of my Xcal2's that I have, so that way we have a more accurate representation of shifting command vs actual and IAT's as well to name a few. If I can get the on-board datalogging feature to work correctly on these I might bring both out and give it a try. I would bring the laptop too but the screen took a sh1t. :mad:

Driller, what size are those tires?

Driller, what size are those tires?


26x9.50-16 Hoosier Quick Time Pro D.O.T. Drag Tires