Mojo Tyre FAQ’s

FAQs

How should I store my Mojo tyres?

Mojo tyres keep their performance best if they are stored away from light (in a tyre bag or black plastic refuse sack) low humidity at normal ambient temperature (20°C/68°F) – do not store Mojo tyres below 0°C/32°F! Remove the plastic protection film from the tyres just before fitting to the rims!

Why is the use of tyre softeners or any kind of tyre treatment prohibited?

The use of tyre softeners can alter the compound of the tyre which can result in a failure of the tyre – safety risk! Most tyre softeners are toxic and can cause cancer. Altering the compound of tyres is not in line with the philosophy of the Rotax MAX Challenge with regards to fair competition with equal equipment.

What does camber mean?

Camber is the angle of the wheel relative to vertical, as viewed from the front. If the wheel leans
in towards the chassis, it has negative camber; if the wheel leans away from the chassis,
it has positive camber (right picture). The cornering force that a tyre can develop is highly dependent on its angle relative to the road surface, and so wheel camber has a major effect on the track surface holding of the kart

What does caster mean?

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical,
as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if the it’s tilted forward, then the caster is negative.

Positive caster tends to straighten the wheel when the kart is traveling forward, and thus is used to enhance straight-line stability.

What does toe in/out mean?

When a pair of wheels are set so that their leading edges are pointed slightly towards each other, this is toe-in (left picture). If the leading edges point away from each other, this is toe-out (right picture). The amount of toe can be measured as the difference between the track widths as measured at the leading and trailing eadges of the tyres or wheels. Toe settings affect three major areas of performance:

  • tyre wear
  • straight-line stability and
  • corner entry handling characteristics

Does the barcode on MOJO tyres have any meaning?

As of 2009 all MOJO tyres are marked with an 8 digit barcode. The barcode of all MOJO tyres is generally beginning with the number 8 which has been accredited from CIK. The remaining 7 digits are given in an random order. The barcode is mainly meant to be used as control instrument at race meetings. The barcode shall guarantee that competitors are only using those tyres which are dedicated to them during an event (as indicated in the sporting regulations of the varies ROTAX MAX Challenges).

Are there Tips & Tricks for MOJO tyres available?

Generally:

Tyres are one of the most important components of your kart and when they are looked after correctly, will have longer durability and better performance.

When your tyres are ‘new’ they will perform at their best. They will not only give you the best cornering grip, but better stability and balance through the corners, as well as maximum braking grip

When your tyres wear out they lose grip. When your tyres are not looked after, they wear out even quicker, with dramatic performance loss. This results in an unstable handling kart with poor performance
So it makes sense to take as much care of your tyres as possible!!

Always check wheel alignment before using your kart. Re-check alignment if you have been involved in an incident or hit a kerb heavily on the track

Always check your preferred tyre pressure before and after you take to the track

After use and when storing your tyres, remove excess air to retain the elasticity of the tyres

When storing tyres keep away from direct sunlight, fluorescent lights, high temperatures and electric motors as ozone gases also effect your tyres. Store tyres in a sealed, non clear bag preferably in a cool area

Be careful not to spill fuel or other hazardous liquids onto your tyres

 

Dry tyre settings:

MOJO D1MOJO D2MOJO D3C2 and CX
CASTERNeutralNeutralNeutralNeutral
CAMBER+ 4mm0 to + 2mm00
TOE OUT+ 2mm+ 2mm+ 2mm0 to +2mm
REAR TRACK1375mm +1385mm +1390mm +
SEAT STAYSYESYESYESOPTIONAL

 

Wet tyre settings:

Damp track:

Leave the dry settings
Fit the wet tyres

Damp trackMOJO W2MOJO CX
Tyre pressure1,2 – 1,5 bar1,5 bar

 

Full wet track:

Full wet trackMOJO W2MOJO CX
Casterfull caster (positive)full caster (positive)
Camber“0” +/- 2mm“0” +/- 2mm
Tracktoe-out 8mm – 12mm (positive)toe-out 8mm – 12mm (positive)
Rear trackoptional to more rear track. Toe-in 5mm per side. Rear wet tyres are narrower than dry tyres. Fitting wet tyres automatically narrows rear track.
Seatoptional
Tyre pressure1 bar1,5 bar

 

Troubleshooting Dry Tyres:

ProblemSolutionProblemSolution
Front of kart pushes when entering corner. Understeer.Increase front tyre pressure 0.05 bar. Or  decrease rear tyre  pressure 0.05 barRear of kart slides when entering corners. Oversteer.Increase rear tyre pressure 0.05 bar. Or decrease front tyre pressure 0.05 bar
Kart bounces in corners.Increase tyre pressure all around 0.05 barKart 2 wheels in corners.Decrease tyre pressure all around 0.05 bar
Kart takes a long time to find grip.Increase pressure all around 0.05 barKart loses grip towards end of race.Decrease pressure all around 0.05 bar

When making a change only make one adjustment at one time. This will give you a clear indication that the particular change has made a difference to your set-up and performance. Remember to log your changes for future reference.

Troubleshooting Wet Tyres:

ProblemSolutionProblemSolution
Front of kart pushes when entering corner. UndersteerIncrease front tyre pressure 0.05 bar. Increase front track (e.g. 10mm to 14mm toe out)Rear of kart slides when entering corner. OversteerIncrease rear tyre pressure 0.05 bar. Decrease front track (e.g. 14mm to 10mm toe out)
General overall lack of grip.Increase tyre pressures all around 0.05 bar. Lift seat position by 10mm[minimalTable][/minimalTable]Kart loses grip towards end of raceDecrease tyre pressure all around 0.05 bar

 

Wet weather set-up is very difficult and requires patience and practice to get right. Getting as comfortable as possible (wet weather clothing) is essential as well as having a confident attitude. Make it as fun as possible whilst being safe. 

Any special procedure for scrubbing in tyres?

Set tyre pressures to preferred settings. Use a reliable tyre gauge

Complete 2 laps at a medium pace without sliding the kart. Gradually increase your speed to full pace allowing a good heat transfer throughout the tyres

Check pressures immediately after finish of driving to establish a good working tyre pressure and temperature. Pressure should not increase more than 0.35 bar

Check tyres for any unusual signs of wear or damage. Re-check tyre balance.

How Important Are Tyre Pressures?

The pressures of your tyres are very important. Too low a pressure will not allow the temperature of the tyre to reach it’s optimum and therefore the correct grip level will not be reached.

Too high a pressure will allow the tyres to work well initially, but as the temperature increases too much, performance of the tyres drop off creating inaccurate lap times and poor performance, with excess tyre wear.

MOJO D1Recommended tyre pressure coldSet pressure at 0.7 bar all aroundMax in pressure hot, 1.05 barMOJO D2Recommended tyre pressure coldSet pressure at 0.65 bar all around

Max in pressure hot, 0.9-1.0 bar

MOJO D3Recommended tyre pressure coldSet pressure at 0.6 bar all around

Max in pressure hot, 0.85-0.9 bar

MOJO W2Recommended tyre pressure coldSet pressure at 1.0 bar all around

Increase in pressure depends on how cool the weather is. Must have an increase in pressure.

MOJO CX and C2Recommended tyre pressure coldSet pressure at 1.5 bar all around

Max pressure hot, 1.85 bar

 

How is a Mojo tyre built up?

BEAD

The bead of the tyre is the area that holds the tyre to the rim. The bead needs to be strong enough to hold the tyre on the rim whilst in use, without popping off the rim, and flexible enough for the tyre to be fitted to the rim and hold air pressure.

SHOULDER

The tyre needs a solid shoulder to enable a good contact between the tyre and the track whilst cornering. The shoulder of the tyre is under continued high loads during usage and connects the contact area of the tyre with the sidewall.

SIDEWALL

The sidewall takes the load of the kart and holds the tyre in place during use. If the sidewall is too soft the tyre will fold under during cornering. If the sidewall is too stiff it will be a very stiff ride and finding grip could be difficult.

CONTACT AREA

The tyre needs to have as much contact area as possible to obtain ‘maximum’ grip. Tyre pressures also determine how much contact area is obtainable.

TYRE SPECIFICATIONS

MOJO D1SL type: Dry-hard compoundRear tyre: 7.1/11.0-5Front tyre: 4.5/10.0-5Recommended pressure cold0.7 bar all aroundMOJO D2SL type: Dry- medium compoundRear tyre: 7.1/11.0-5Front tyre: 4.5/10.0-5Recommended pressure cold0.65 bar all around
MOJO D3SL type: Dry- medium/softRear tyre: 7.1/11.0-5Front tyre: 4.5/ 10.0-5Recommended pressure cold0.6 bar all aroundMOJO W2SL type: WETRear tyre: 6.0/11.0-5Front tyre: 4.5/10.0-5Recommended pressure cold1.0 bar all around
MOJO CX and C2SL type: Medium/groovedRear tyre: 5.0/11.0-5Front tyre: 4.0/10.0-5Recommended pressure cold1.5 bar all around

 

Tyre temperature - needle or a non-contact IR thermometer?

It is an option to use a needle pyrometer at all your tests as the tyres cool down quickly and measuring just the surface temperature is not accurate enough.

Why should I follow the procedure on the tyre labels?

We found out that the “running in of the tyre” procedure is the best method of controlling the increase of temperature and pressure within the tyres, thus providing the best optimal grip level. The tyres remain stable for longer as the heat cycle assists in “curing” the tyre properly whilst in use. During this process of gradually increasing temperature, pressure and speed, the tyres also have the best chance to wear correctly.

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