Road Racing Tuning Guide

Tires

Compound	Best For	Class	Width F	Width R	PSI F	PSI R	Notes
Sport	ROAD — D–B class	D – B	225–245	235–255	29	28	Budget road racing, good balance
Semi-Slick	ROAD — A–S1	A – S1	245–265	255–285	28	27	Best blend of grip & top speed
Slick Race	ROAD — S1–X	S1 – X	265–295	275–315	27	26	Max grip — choose narrower to reduce drag
Rally	MIXED — Road + dirt	Any	245–265	255–285	25	24	Sprint/road events on mixed routes
Snow	SNOW — Winter sprint	Any	215–235	225–255	27	26	Required on snow/ice road events

Losing traction → drop PSI 1–2 · Long straight sluggish → try narrower tires to cut drag

Tire Width

Power	RWD Front	RWD Rear	AWD Front	AWD Rear
Under 300 hp	215–235	245–265	225–245	235–255
300–500 hp	225–245	255–280	235–255	245–270
500–700 hp	235–255	270–295	245–265	260–285
700–1000 hp	245–265	285–315	255–275	275–300
1000+ hp	260–280	305–345	265–285	290–315

Losing grip → widen rear 5–10mm · Top speed drag high → narrow rear tires 5–10mm

Gearing — ~0.30–0.50 lower than circuit for same power level

Under 180 mph	3.80 – 4.10	180 – 210 mph	3.30 – 3.70
210 – 240 mph	2.90 – 3.30	240 – 270 mph	2.50 – 2.90
270+ mph	2.20 – 2.60	Rule: hit limiter in top gear near end of longest straight

Limiter hits early in top gear → lower Final Drive · Bogging on corner exits → tighten gears 2–3

6-Speed

Under 185 mph

~200–450 hp

Mult.0.78

Final Drive	3.80
1st	3.20
2nd	2.50
3rd	1.95
4th	1.52
5th	1.19
6th	0.93

7-Speed

185–210 mph

~400–650 hp

Mult.0.80

Final Drive	3.40
1st	3.20
2nd	2.56
3rd	2.05
4th	1.64
5th	1.31
6th	1.05
7th	0.84

8-Speed

210–235 mph

~600–850 hp

Mult.0.82

Final Drive	3.10
1st	3.30
2nd	2.71
3rd	2.22
4th	1.82
5th	1.49
6th	1.22
7th	1.00
8th	0.82

9-Speed

235–265 mph

~800–1100 hp

Mult.0.84

Final Drive	2.80
1st	3.40
2nd	2.86
3rd	2.40
4th	2.02
5th	1.70
6th	1.43
7th	1.20
8th	1.01
9th	0.85

10-Speed

265+ mph

~1000+ hp

Mult.0.86

Final Drive	2.50
1st	3.50
2nd	3.01
3rd	2.59
4th	2.23
5th	1.92
6th	1.65
7th	1.42
8th	1.22
9th	1.05
10th	0.90

Gearing Quick Adjustments

Hitting limiter before end of straightLower Final Drive by 0.10–0.20 or add a gear
Not reaching limiter in top gearRaise Final Drive — too much gear for the power
Bogging on corner exitRaise Final Drive slightly or lower 1st gear ratio
Long slow hairpin sectionTighten gears 1–3 by 0.05–0.10
Mostly sweepers, few hairpinsSpread gears further — gap between top gears matters
Too many unused top gearsRemove a speed or tighten the top-end spread

Alignment

Camber

Front	-1.0° to -2.0°
Rear	-0.8° to -1.3°

Understeer on high-speed sweepers → slightly more negative front camber · Rear sliding first → reduce rear camber

Toe

Negative = in · Positive = out

Front	0° to +0.2°
Rear	-0.3° to -0.5°

Sluggish turn-in → add front toe-out · Snap oversteer at speed → add more rear toe-in

Caster

Angle

5.0° to 6.5°

Car drifting on high-speed straights → raise caster · Slow self-centering on sweepers → raise caster

Antiroll Bars — RWD

Stiffer front = less oversteer · Stiffer rear = less understeer · The gap matters more than the values

Front	20 – 30
Rear	15 – 22
Note	Slightly softer than circuit — fewer sharp corners

Oversteer on sweepers → stiffen front ARB · Understeer → soften front or stiffen rear ARB

Antiroll Bars — AWD/FWD

Stiffer rear reduces AWD/FWD understeer · FWD: very soft rear allows rotation

AWD Front	18 – 25
AWD Rear	25 – 35
FWD Front	12 – 22
FWD Rear	22 – 35

AWD/FWD understeer → stiffen rear ARB · Traction loss over bumps → soften rear ARB

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 225–375 R 250–400
Sport (2,600–3,400)	F 375–550 R 400–575
Muscle (3,400–4,200)	F 500–725 R 525–750
Heavy (4,200+ lbs)	F 650–900 R 675–925

Traction loss over road bumps → soften springs · Excessive body roll → stiffen within weight range

Springs — Notes

Rear heavy car	Rear springs stiffer
Front heavy car	Front springs stiffer
Stiff platform	Min may exceed lower bound — use min
Rule	Match stiffness to axle weight class

Rebound

Controls extension speed · Stiffer front = resists dive · Stiffer rear = resists squat

Front	6.5 – 8.5
Rear	5.5 – 7.5

Car wallowy → raise rebound · Bouncing over bumps → rebound too low

Bump

Controls compression speed · Set bump first · Rebound = bump × 2

Front	3.5 – 5.5
Rear	3.0 – 5.0

Skipping over bumps → lower bump · Diving hard on entry → raise front bump

Aero

Front	Medium – High
Rear	Medium — not always max
Balance target	0.42 – 0.48
Note	Max rear aero costs top speed — find the balance

Losing top speed on long straights → reduce rear aero 2–4 units · Corner instability → raise rear aero back up

Aero Balance Guide

Under 0.40	Too rear — oversteer at speed
0.40 – 0.45	Slight rear — RWD friendly
0.45 – 0.50	Neutral — ideal for road racing
Over 0.50	Front bias — reduces oversteer

Brake — RWD

Balance	55 – 60% front
Pressure	90 – 100%

Rear locking under hard braking → raise front balance % · Front locking on entry → lower front balance %

Brake — AWD / FWD

AWD Balance	52 – 56% front
FWD Balance	58 – 65% front
Pressure	90 – 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

RaceRoad & circuit 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

Diff type is the foundation — choose based on discipline before tuning values · Wrong type fundamentally changes car behaviour and cannot be compensated

Differential — RWD

Acceleration	30 – 50%
Deceleration	20 – 35%
Note	Higher decel than circuit for high-speed stability

Rear unstable under braking → raise decel · Wheelspin on long exits → raise accel

Differential — AWD

Front

Acceleration	15 – 25%
Deceleration	5 – 10%

Rear

Acceleration	35 – 50%
Deceleration	20 – 35%

Center

Balance

50 – 60% rear

AWD understeer on entry → lower front accel · Exit traction weak → raise rear accel

Handling Adjustments

Oversteer at high speed (RWD)Increase rear aero / raise diff decel
Understeer on fast sweepersReduce front aero / soften front ARB
Loose under heavy brakingMove brake bias forward / raise diff decel
Poor turn-in to fast cornersMore front camber / slight front toe out
Bouncy over road surfaceLower bump damping both axles
Snapping on corner exitLower diff accel / soften rear ARB

Top Speed / Aero Fix

Losing top speed vs othersReduce rear aero 1–2 clicks / check FD isn't too high
Losing rear stability at speedAdd rear aero before stiffening suspension
Aero balance too low (<0.40)Raise front aero to max first
Still unbalanced after max frontLower rear aero slightly
No aero options on carUse rear toe-in & diff decel to compensate

Made by Caspeyy

Last updated: May 25, 2026