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Circuit Tuning Guide

Technical Circuits — Tight Corners, Short Straights — Tune for Cornering Grip & Maximum Downforce

Tires
CompoundBest ForClassWidth FWidth RPSI FPSI RNotes
StreetROAD — CasualD – B205–225215–2353029Low grip, saves PI
SportROAD — CircuitC – A225–245235–2652928Good all-round road tire
Semi-SlickROAD — CircuitA – S1245–265255–2852827Track-focused, road legal
Slick RaceROAD — CircuitS1 – X265–295275–3152726Max tarmac grip, no offroad
RallyMIXED — Road + dirtAny245–265255–2852524Compromise on both surfaces
SnowSNOW — Winter eventsAny215–235225–2552726Required for snow/ice surfaces
Losing traction mid-corner → drop PSI 1–2 · Not enough grip → match compound to surface first
Tire Width
PowerRWD FrontRWD RearAWD FrontAWD Rear
Under 300 hp215–235245–265225–245235–255
300–500 hp225–245255–280235–255245–270
500–700 hp235–255270–295245–265260–285
700–1000 hp245–265285–315255–275275–300
1000+ hp260–280305–345265–285290–315
Losing corner grip → widen rear 5–10mm · FWD understeer → widen front 5–10mm vs RWD
Gearing
Alignment
Camber
Front-1.5° to -2.5°
Rear-1.0° to -1.5°
Understeer mid-corner → more negative front camber · Rear instability → reduce rear camber
Toe
Negative = in · Positive = out
Front0° to +0.2°
Rear-0.2° to -0.4°
Sluggish turn-in → add front toe-out · Snap oversteer → add rear toe-in
Caster
Angle5.5° to 7.0°
Car unstable on straights → raise caster · Slow steering return after corners → raise caster
Antiroll Bars — RWD
Stiffer front = less oversteer · Stiffer rear = less understeer · The gap matters more than the values
Front25 – 35
Rear15 – 25
GoalStiffer front reduces oversteer
Oversteer → stiffen front ARB or soften rear · Understeer → stiffen rear ARB or soften front
Antiroll Bars — AWD/FWD
Stiffer rear reduces AWD/FWD understeer · FWD: very soft rear allows rotation
AWD Front20 – 28
AWD Rear28 – 38
FWD Front15 – 25
FWD Rear25 – 38
AWD/FWD understeer → stiffen rear ARB · Traction loss over bumps → soften rear ARB slightly
Springs
lbs/in — Ride Height: minimum available
Rear = Front + 20–30 lbs/in · Pick front by weight, add ~25 for rear
Light (<2,600 lbs)F 250–425
R 275–450
Sport (2,600–3,400)F 400–600
R 425–625
Muscle (3,400–4,200)F 550–800
R 575–825
Heavy (4,200+ lbs)F 700–1000
R 725–1025
Traction loss over bumps → soften springs · Too much body roll → stiffen springs within weight range
Springs — Notes
Rear heavy carRear springs stiffer
Front heavy carFront springs stiffer
Stiff platformMin may exceed lower bound — use min
RuleMatch stiffness to axle weight class
Rebound
Controls extension speed · Stiffer front = resists dive · Stiffer rear = resists squat
Front7.0 – 9.0
Rear6.0 – 8.0
Car wallowy → raise rebound · Bouncing over bumps → rebound too low
Bump
Controls compression speed · Set bump first · Rebound = bump × 2
Front4.0 – 6.0
Rear3.5 – 5.5
Skipping over bumps → lower bump · Diving hard on entry → raise front bump
Aero
FrontMaximum available
RearMaximum available
Balance target0.45 – 0.50
Losing top speed on long straights → reduce rear aero 2–4 units · Corner instability → raise rear aero back up
Aero Balance Guide
Under 0.40Too rear — oversteer
0.40 – 0.45Slight rear — RWD friendly
0.45 – 0.50Neutral — ideal
Over 0.50Front bias — less oversteer
Brake — RWD
Balance55 – 60% front
Pressure90 – 100%
Rear locking under braking → raise front balance % · Front locking into corners → lower front balance %
Brake — AWD / FWD
AWD Balance52 – 56% front
FWD Balance58 – 65% front
Pressure90 – 100%
Rear locking (AWD) → lower front balance slightly · Rear stepping out (FWD) → raise front balance %
Differential Types
StockLow class / saves PI — limited or no tuning available
RaceCircuit & road racing — full accel/decel tuning range
DriftRoad drift — high lock bias, tuned for sustained slides
OffroadCross country / offroad drift — loose surface compliance
RallyMixed events — road & dirt compromise
DragStraight line only — maximum lock, launch focused
Unexpected handling → confirm Race diff is equipped before adjusting accel/decel
Differential — RWD
Acceleration35 – 55%
Deceleration15 – 30%
High power RWDAccel 50–60%
Wheelspin on exit → raise accel · Car snapping under trail braking → raise decel
Differential — AWD
Front
Acceleration15 – 25%
Deceleration5 – 10%
Rear
Acceleration40 – 55%
Deceleration20 – 30%
Center
Balance50 – 60% rear
AWD understeer → lower front accel · Exit wheelspin → raise rear accel · More rotation → shift center rearward
Handling Adjustments
  • Oversteer on exit (RWD)Lower diff accel / soften rear ARB
  • Understeer (AWD/FWD)Soften front ARB / stiffen rear ARB
  • Loose under brakingRaise diff decel / move brake bias forward
  • Poor turn-inMore front camber / increase front toe out
  • Rear sliding at speedIncrease rear downforce / stiffen rear ARB
  • Bouncy over bumpsLower bump damping on affected axle
Aero Balance Fix
  • Balance too low (<0.40)Raise front downforce to max first
  • Still too low after max frontLower rear downforce slightly
  • Understeer at speedReduce front downforce slightly
  • Oversteer at speedIncrease rear downforce
  • No aero optionsUse ARB & diff to compensate
Made by Caspeyy
Last updated: May 25, 2026