📻 Track Radio — off air
Lights up when the track is broadcasting — check back on race day.
Get rain-out & schedule alerts
We’ll email you when Sully MX posts an urgent update. No account, unsubscribe anytime.
Sully MX
Lynnville, Iowa
Weather & Rideability
TodayAbout
Sully MX (also known as The Bull Ring MX) is a motocross track near Lynnville in Jasper County, Iowa, that has hosted AMA District 22 and Iowa Moto Series events. Its current operating status is unconfirmed — verify before visiting.
Track DNA — what the dirt is really like
Intermediate- ▸Loam — the good stuff. Takes ruts, holds a line, and rewards smooth riding. This is the surface most tires and stock suspension are happiest on.
- ▸Drains well — typically prime 1–2 days after a soak, when it’s tacky instead of slick.
- ▸High silt (66%) — this dirt turns to DUST when dry. Expect water trucks, hazy late motos, and pack extra air-filter prep.
- ▸Genuine elevation (~33 m of relief) — real uphills and downhill braking zones, not just man-made jumps. Brakes and fitness matter here.
- ▸Wettest months: May, Jun, Jul — highest mud/cancellation risk. Prime window: May, Aug, Sep.
What do these terms mean? ▾
- Sand / Silt / Clay %:
- What the topsoil is made of. More sand = looser and faster-draining. More clay = harder, slicker when wet. Silt is the fine dust-maker in between.
- Loam:
- A balanced sand/silt/clay mix — the tacky, rut-forming dirt riders love.
- Blue-groove:
- When dry hard-pack gets polished by tires into a shiny dark racing line — grippy for some tires, ice for others.
- Drainage class:
- USDA’s rating of how fast this ground sheds water — it predicts how soon after rain the track is rideable.
- Soil series:
- The official USDA name for this exact soil type (like a breed name for dirt).
- Relief:
- How much the ground rises and falls within the track’s ~1 km square — flat, rolling, or genuinely hilly.
Tires that work on this dirt
Dunlop · Front & Rear
Geomax MX33
The most popular soft-to-intermediate tire — safe all-around pick.
View on Amazon →Pirelli · Rear
Scorpion MX32 Mid-Soft
Versatile mid-soft compound for loamy, mixed dirt.
View on Amazon →Picked for this track's intermediate surface · Amazon affiliate links — MWR earns a small commission at no extra cost to you.
Topsoil (0–15 cm) composition from USDA SSURGO soil survey. A guide to typical conditions — actual surface varies with prep, weather, and watering.
Dial It In for Sully MX
Setup tuned to this track's verified soil & terrain
Air filtration · Clean spare air filter
Dry mixed dirt still kicks up fine dust — a clean, properly oiled spare keeps power consistent across a long race day.
Gearing · Rear sprocket for the climbs
Real elevation here means sustained uphill drive — a rear sprocket tuned slightly lower keeps you in the meat of the powerband on the climbs.
Brakes & suspension · Fresh brake pads + sag tools
Genuine downhill faces work the front brake and fork hard. Fresh pads and a dialed race sag (sag/spanner tools) pay off on hilly layouts like this.
As an Amazon Associate we earn from qualifying purchases. Recommendations are general guidance from soil/terrain data — not a substitute for your own setup.
Riding Season
Apr – OctPractical riding season Apr – Oct; best in May, Aug, Sep (warm + dry); wettest / mud risk May, Jun, Jul; peak heat Jul (~84°F).
Best months to ride in Iowa→Based on 2019-2024climate normals (Open-Meteo / ERA5) at this location — a planning guide; check the track's Facebook for current conditions before you haul.
Practice & Race Schedule
Practice days, race dates, and fees change week to week and are posted by the track — most run their schedule through Facebook. Always confirm the current days before you load up and head out.
Amenities
Contact
Worth the Haul
Nearest essentials (approx. straight-line miles)
Fuel
Hospital · Grinnell Regional Medical Center
Camping · Kellogg RV Park
Lodging · Hotel Grinnell
Data: OpenStreetMap. Verify before relying on it for an emergency.