RE: unlimited mt class.........
sk8z27, the following was taken directly from the RC Pro Series website regarding the differences between a standard monster truck and an Arena/Unlimited/Outlaw (whatever your area may call it):
Standard Monster Truck
Scale - 1/10-1/8
Description:
To be a Standard MT, the lowest point of the engine must sit at least 1.5" inches above the lowest point along the front-back centerline when compressed (usually the "skid plates").
To tech questionable MTs, remove the wheels, place MT on flat surface, compress the vehicle fully and a ruler (or 1.5" gauge) could be used vertically to measure the engine above the surface.
The following trucks are examples that fit within the above definition: T (and S) -Maxxes, Savage, MGT, Revo, TNX/TC and LST.
Minimum track width - - - - - - - - - - - - - Continuous 10 feet (same as 8th scales)
Wheel base - - - - - - - - - - - - - - - - - - - Minimum 12 inches
Transmission - - - - - - - - - - - - - - - - - - 1, 2 or 3 speed are OK
Engine - - - - - - - - - - - - - - - - - - - - - - - .12ci to .28c
Carb ------------------------------------------------- No size restriction. Carb must mount securely to the motor.
Exhaust ------------------------------------------- Pipes must meet the 85 decibel limit and have no movable parts in them.
Minimum weight - - - - - - - - - - - - - - - - .12ci to .18ci Small blocks: 2750grams (~6 pounds), .15 to .28 Big blocks: 4300 grams (~9.5 pounds)
Maximum weight for the safety of turn marshals ------------------- 13 pounds 6 ounces
Fuel Tanks - - - - - - - - - - - - - - - - - - - - Single fuel tanks only.
Bodies - - - - - - - - - - - - - - - - - - - - - - - Truck or SUV (no buggy or car bodies allowed )
Bumpers - - - - - - - - - - - - - - - - - - - - - -Bumpers are optional. If used, must not extend further than 1" past the body on the front and rear.
Rear Spoiler/wing - - - - - - - - - - - - - - - A spoiler/wing is optional.
Skid Plates - - - - - - - - - - - - - - - - - - - -Skid Plates must not extend further than 1" past the body on the front and rear.
Wheels --------------------------------------------- Must be manufactured for Monster Trucks.
Wheel Mounting -------------------------------- Wheel mounting - Must be securely mounted at all times.
Tires - - - - - - - - - - - - - - - - - - - - - - - - -Must be rubber only and currently available to the public (i.e. in hobby shops at least 2 weeks prior to event) as a Monster Truck tire. No tires created for other vehicle types even if they fit the specifications will be allowed. Cutting or modifying the tread is allowed. Modifying the tire carcass by sectioning or narrowing is prohibited. Due to the varying sizes of wheels available for Monster Trucks it IS legal to trim the mounting bead of a tire produced for the Monster Truck class to make it fit a Monster Truck rim. Example - Bowtie on a REVO wheel. All tire measurements reference the carcass dimensions and does not include the tread depth or width.
Tire diameter- - - - - - - - - - - - - - - - - - - Minimum - 5.1" (mounted)
Tire width - - - - - - - - - - - - - - - - - - - - - Minimum - 2.75"(mounted)
Race lengths- - - - - - - - - - - - - - - - - - - Qualifiers - 5 to 10 minutes, Main events - 15 to 60 minutes
NOTES:
1. All Standard MT's will run in the same class. Big block/small block is no longer an issue, larger displacement engines have a heavier minimum weight to compensate.
1/8th Arena Truck Class
Scale - 1/10-1/8
Description:
Any Monster Truck that does not 100% meet the Standard MONSTER TRUCK specifications while still meeting the below guidelines will run in the Unlimited Class. Standard Monster Trucks may also enter the Outlaw class.
Minimum track width - - - - - - - - - - - - - Continuous 10 feet (same as 8th scales)
Wheel base - - - - - - - - - - - - - - - - - - - Minimum 12 inches
Transmission/diff - - - - - - - - - - - - - - - - - - 1, 2 or 3 speed are OK
Engine - - - - - - - - - - - - - - - - - - - - - - .12ci to .28ci
Carb ------------------------------------------------- No size restriction. Carb must mount securely to the motor.
Exhaust ------------------------------------------- Pipes must meet the 85 decibel limit and have no movable parts in them.
Minimum weight - - - - - - - - - - - - - - - - 2750grams (~6 pounds)
Maximum weight for the safety of turn marshals ------------------- 13 pounds 6 ounces
Fuel Tanks - - - - - - - - - - - - - - - - - - - - Single fuel tanks only.
Bodies - - - - - - - - - - - - - - - - - - - - - - - Truck or SUV (no buggy or car bodies allowed )
Bumpers - - - - - - - - - - - - - - - - - - - - - -Bumpers are optional. If used, must not extend further than 1" past the body on the front and rear.
Rear Spoiler/Wing - - - - - - - - - - - - - - - A spoiler/wing is optional.
Skid Plates - - - - - - - - - - - - - - - - - - - -Skid Plates must not extend further than 1" past the body on the front and rear.
Wheels --------------------------------------------- Must be manufactured for Monster Trucks.
Wheel Mounting -------------------------------- Wheel mounting - Must be securely mounted at all times.
Tires - - - - - - - - - - - - - - - - - - - - - - - - -Must be rubber only and currently available to the public (i.e. in hobby shops at least 2 weeks prior to event) as a Monster Truck tire. No tires created for other vehicle types even if they fit the specifications will be allowed. Cutting or modifying the tread is allowed. Modifying the tire carcass by sectioning or narrowing is prohibited. Due to the varying sizes of wheels available for Monster Trucks it IS legal to trim the mounting bead of a tire produced for the Monster Truck class to make it fit a Monster Truck rim. Example - Bowtie on a REVO wheel. All tire measurements reference the carcass dimensions and does not include the tread depth or width.
Tire diameter- - - - - - - - - - - - - - - - - - - Minimum - 4.55" (mounted)
Tire width - - - - - - - - - - - - - - - - - - - - - Minimum - 2.25"(mounted)
The Panther LP is referenced for this size and will be the absolute smallest tire legal.
Race lengths- - - - - - - - - - - - - - - - - - - Qualifiers - 5 to 10 minutes, Main events - 15 to 60 minutes
NOTES:
1) All Unlimited MT's will run in the same class.
Just take these rules to your local track, and see if they will use them as guidelines. I know that at our local indoor track, the controversy has been going on for a while, but has been resolved by the separation of the two classes.
I hope that this helps.
p.s.
These are last years rules, but should be a good base to start with.