Do SCORE and BITD limit wheel diameter sizes???

Chris Tobin

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While attending PRI this weekend I was speaking to a brake manufacturer and the rep told me that SCORE and BITD limit wheel diameter to 17-inches. He said they would love to run 20-inch wheels to fit larger brake components but that it was not allowed. I went through the BITD online rulebook again and cant find anything saying wheel diameter limits are in place, but I suppose I may have missed it. I do not have a SCORE rulebook to look through.

Does anyone know if he is correct or mistaken?

I am running 37-inch diameter tires on my Duramax project truck and currently have 17-inch wheels but I was considering going to a 20-inch wheel to fit larger brake components.

What do you guys think? Is loosing 1.5-inches of sidewall too big of a loss on a 37-inch tire to overcome braking improvements on a big/heavy diesel powered truck?

Is anyone running a 20-inch wheel currently in BITD or SCORE?

Thanks for any suggestions/clarifications/advice.
 

Jorge Rodriguez

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I know that COPS and Vanderwey were running 42" tires on 20" wheels in SCORE.
 

Chris Tobin

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I know that COPS and Vanderwey were running 42" tires on 20" wheels in SCORE.
Thanks, I thought some were running 20s, I wonder if they still are and if they liked them or not... Anyone have any info...
 

TRON3000

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The only people running 20" wheels ran a 42" tire. The tire and wheel weight tears stuff up. BITD has a 40" tire limit so most are running 39's or 40's. I think you are going to want to stick with 17" wheels. You will get a big enough brake package with 14" rotors. The biggest brake issues come from not enough pressure, run a hydroboost and you will have plenty of stopping power. Most race tires only come in 15", 17", or 20", 15" wheel is for a 33 or 35 tire, 17" wheel is for 37-39-40 tire, and 20" wheel is for 42" tires. Don't go 20
 

kenny hicks

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my name is kenny hicks i am with the cops racing team. please contact me at 1-310-383-1750 about the wheel you want.
 

kenny hicks

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hey Chris, how it going? I was wondering if you were still interested in the tires. If so, could you please contact me at 1310-383-1750. or at 1-818-736-2145
thanks again
 

bobsson

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The only people running 20" wheels ran a 42" tire. The tire and wheel weight tears stuff up. BITD has a 40" tire limit so most are running 39's or 40's. I think you are going to want to stick with 17" wheels. You will get a big enough brake package with 14" rotors. The biggest brake issues come from not enough pressure, run a hydroboost and you will have plenty of stopping power. Most race tires only come in 15", 17", or 20", 15" wheel is for a 33 or 35 tire, 17" wheel is for 37-39-40 tire, and 20" wheel is for 42" tires. Don't go 20
I agree with a lot of this, however I run 17 inch rims with 35s to limit how much weight I've got hammering parts. Also switching to hydroboost made a huge difference in stopping allowing the brakes to really grab and stop the tire even at higher speeds.
 

Chris Tobin

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I agree with a lot of this, however I run 17 inch rims with 35s to limit how much weight I've got hammering parts. Also switching to hydroboost made a huge difference in stopping allowing the brakes to really grab and stop the tire even at higher speeds.
17-inch wheel with 35-inch tire is very similar to a 20-inch wheel and a 37-inch tire is it not?

My truck has Hydroboost braking already, but I would still like more and better braking. Wilwood builds a kit for the 3/4- and 1-ton GM trucks but it uses a massive 16-inch rotor and equally massive 6-piston caliper... I think the factory rotors are just under 13-inch in front and 13-inch in the rear with 4-piston calipers...

I honestly think going to the 20 might weight a little less than the 17-inch combination or at least not much more and the brakes will have MUCH better stopping power to whoa the beast down!!!
 

bobsson

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17-inch wheel with 35-inch tire is very similar to a 20-inch wheel and a 37-inch tire is it not?

My truck has Hydroboost braking already, but I would still like more and better braking. Wilwood builds a kit for the 3/4- and 1-ton GM trucks but it uses a massive 16-inch rotor and equally massive 6-piston caliper... I think the factory rotors are just under 13-inch in front and 13-inch in the rear with 4-piston calipers...

I honestly think going to the 20 might weight a little less than the 17-inch combination or at least not much more and the brakes will have MUCH better stopping power to whoa the beast down!!!
It will still be a bit heavier than the 17 and 35s. If you choose the same rim style and tire model.
 

PaulW

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Compare electric boost with hydroboost and tell us the difference. "ABS Power brake" sells E-boost setups..
 

Chris Tobin

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It will still be a bit heavier than the 17 and 35s. If you choose the same rim style and tire model.
Yes, but I am running 17/37 now so going 20/37 would be be what I go to with the larger brakes if I go that route. And I think that would be similar in weight.
 

Dirty Harry

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Yes, but I am running 17/37 now so going 20/37 would be be what I go to with the larger brakes if I go that route. And I think that would be similar in weight.

I don't think that they will be similar in weight. BFG lists 73 pounds for a 37 for both a 17 and 20 inch rim, the same weight. But the wheel will be heavier. A 17-inch Trailready HD17 weighs 35 pounds but a HD20 weighs 50 pounds.
 

bobsson

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Yes, but I am running 17/37 now so going 20/37 would be be what I go to with the larger brakes if I go that route. And I think that would be similar in weight.
It's not similar in weight, you're going to be adding probably 35+ pounds per wheel. The bigger brakes will help slow down, probably a little bit, however you're going to be putting a lot more pressure on your wheel bearings.
 

Chris Tobin

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It's not similar in weight, you're going to be adding probably 35+ pounds per wheel. The bigger brakes will help slow down, probably a little bit, however you're going to be putting a lot more pressure on your wheel bearings.
I don't think that they will be similar in weight. BFG lists 73 pounds for a 37 for both a 17 and 20 inch rim, the same weight. But the wheel will be heavier. A 17-inch Trailready HD17 weighs 35 pounds but a HD20 weighs 50 pounds.

Thanks guys... I'll figure out the weights for sure before pulling the trigger to go to the 20 if I do decide to do it... I looked up the pics I took of weighing the 17-inch KMC Enduro Beadlocks I am currently running and they were 39.6-pounds.

American Force Wheels builds a 20-inch beadlock that is forged, I am not sure what the weight is with that wheel...

I am surprised the tire would weigh the same, I would have suspected that the 20-inch version would be at least a little lighter than the 17-inch version because there would be less sidewall rubber and structure, but the same amount of tread rubber and structure...

Another factor that will come into my decision is writing articles and showing our readers the upgrades...

I was hoping to get driving impressions from someone that has driven on a 20-inch combination...
 

bobsson

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Thanks guys... I'll figure out the weights for sure before pulling the trigger to go to the 20 if I do decide to do it... I looked up the pics I took of weighing the 17-inch KMC Enduro Beadlocks I am currently running and they were 39.6-pounds.

American Force Wheels builds a 20-inch beadlock that is forged, I am not sure what the weight is with that wheel...

I am surprised the tire would weigh the same, I would have suspected that the 20-inch version would be at least a little lighter than the 17-inch version because there would be less sidewall rubber and structure, but the same amount of tread rubber and structure...

Another factor that will come into my decision is writing articles and showing our readers the upgrades...

I was hoping to get driving impressions from someone that has driven on a 20-inch combination...
By going up in diameter you're increasing the heaviest part of the tire, the tread. A 35x12.5R17 BFG TKO2 weighs 60 pounds, the 37x12.5R20 is 70.
 

Chris Tobin

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By going up in diameter you're increasing the heaviest part of the tire, the tread. A 35x12.5R17 BFG TKO2 weighs 60 pounds, the 37x12.5R20 is 70.
I am not going up in diameter, I already am running 37X12.50R17 tires now... IF I make a change it will be in wheel diameter not tire diameter...

That is what I am looking for experiences on, someone who has run 37X12.50R20s... Sorry if I wasn't clear earlier.

I understand that a larger tire is heaver, but a larger wheel is not necessarily heavier especially going from cast like I have now to forged as I would if I go to the American Force wheel...
 

Chris Tobin

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I just looked up weight on the BFG Mud Terrain KM2 and the 37/17 weighs 73.9-pounds while the 37/20 weighs 72.6-pounds so as I expected the tire weight is slightly reduced going from a 17-inch wheel to a 20-inch wheel.

Now I'll have to get some wheel weight numbers on the ones I am thinking about...
 

BigBlue&Goldie

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Why do you think you need bigger brakes than a trophy truck? Sure, your truck weighs more than a trophy truck, but unless you sink MAJOR bucks into it, you won't be going nearly as fast. I'd be much more concerned with spindles and hubs than brakes. If you haven't priced those out, brakes are the least of your concerns.
 

Slippery P

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You will have a very small side wall with a 37/20, heavy vehicle= pinch flats.
Everybody would love to run a bigger brake package, but you sacrifice that with a bigger wheel and more likely pinch flats.
 
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