How to Optimize your Tyre Pressures and Temperatures on your Caravan/Camperinsert image here: and your150 x 80mm vehicle www.kimberleygroup.com.au 20121126 2 Importance of Optimum Tyre Pressure and Temperature Table of Contents 1. Why is tyre pressure and temperature so crucial? 2. What is the link between Tyre Pressure and Temperature? 3. Getting the starting pressure right 4. Adjusting the pressure with the 4PSI rule 5. Adjusting the pressure to the optimum 6. TPMS 7. Suggested Pressure and Speed for conditions 8. Conversion Table 9. Is there an Optimum Tyre Size? 10. Acceleration, Braking and Load Transfer 11. Specifications of TPMS 12. TPMS Kit from Kimberley 13. Tyre Markings/ Tyre Size 14. Tyre Ageing kimberleygroup.com 3 Importance of Optimum Tyre Pressure and Temperature This eBook addresses the question: How much of Australia do you want to experience? kimberleygroup.com 4 Importance of Optimum Tyre Pressure and Temperature Why is Tyre Pressure so crucial? Your tyre’s inflation pressure is measured as pounds per square inch, (psi) or “Bar (metric). The maximum recommended psi for your tyres printed right on them. However, manufacturers may print a lower recommended psi than your tyre can truly handle because the lower inflation rate will give you a softer ride. If you over inflate your tyres, you might cause some safety hazards. You’ll definitely wear out the tyres more quickly. A tyre that is over inflated shows more wear along the center width of the tyre than along its edges. When your tyres develop uneven tread wear, it shortens the overall life expectancy of your tyre. The proper inflation level on your tyres also affects how much load your car can carry. Every vehicle and camper trailer/ caravan comes with a tyre-load rating that tells you the maximum weight that your tyres can bear. However the tyre-load rating assumes properly inflated tyres. If you over inflate your tyres and overload the weight, you’re creating the perfect recipe for a tyre to blow out. Over or Under-inflation contributes to: 1. Rapid and uneven tread wear 2. A loss in fuel economy, 3. Poor vehicle handling 4. Excessive heat buildup which may lead to tyre failure. kimberleygroup.com 5 Importance of Optimum Tyre Pressure and Temperature What is the link between Tyre Pressure and Temperature? Understanding how temperature affects tires and their pressure is important. • Tire pressure measures the amount of air in your tires at a given tempera- ture. • Changes in the ambient air tempera- ture will affect your tire pressure. For every 5-degrees celius fluctuation in temperature, your tires gain or lose one PSI of pressure. • Changes in the temperature from heat generated by the tyre caused by friction between your tires and the road will increase tire pressure. • As the temperature of your tires rise, so will the pressure levels. • This increase can cause overinflated tires to blow or underinflated tires to appear acceptable. • This makes it important to consistently check your levels because in the morning after a near zero degrees overnight camp in the desert, your ambient temperature may rise from low single digits to high 30s or even in the 40s! • This wild change in temperature in the outback makes it even more important to optimize your tyre pressures as you travel. Stay safe, have better performance & save repair downtime and money! kimberleygroup.com 6 Importance of Optimum Tyre Pressure and Temperature Getting the Starting Pressure Right The Starting point for your Vehicle’s/ Camper Trailer/Caravan Tyre Pressure when cold is set by: Every tyre has a maximum inflation pressure stamped on the side somewhere. This is the maximum pressure the tyre can safely achieve under load. It is not the pressure you should inflate them to. There is a recommended pressure on the door pillar sticker. You can use that as a “starting point” or you can use the “max. pressure-10%” theory. According to a lot of travellers on many internet forums you can get the best performance by inflating them to 10% less than their recommended maximum pressure. It’s a rule of thumb, and is just a starting point which we will refine from so dont be concerned if this appears to be “hear-say”. From my experience it does seem to provide a better starting point for adjusting tyre pressures. kimberleygroup.com 7 Importance of Optimum Tyre Pressure and Temperature Adjusting the Pressure with “4PSI” rule of thumb • After you inflate all tyres to either the pressure recommended by the manufacturer, or the maximum pressure-10%, tow your caravan for say a distance of 100 klm. We are assuming the ambient was cool and hence it is called a “cold tyre” reading. • Upon stopping, immediately recheck your tyre pressure while the tyre is still warm. • If your tyre pressure reading is greater than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then the tyres are getting too hot and your starting tyre pressure was too low. • Under inflated tyres wear unevenly and lead to increased fuel consumption. They can also impair the handling of the vehicle in the areas of braking and handling. • If the tyre pressure reading is less than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then your starting tyre pressure was too high. • With off-road conditions, the guide could be “6PSI” instead of “4PSI” • You will need to run the test again (once the tyre has completely cooled) with less pressure until you find the right balance. kimberleygroup.com 8 Importance of Optimum Tyre Pressure and Temperature Adjusting the Pressure to the Optimum! You can adjust daiy the pressure for optimum conditions as the ambient temperature and road conditions change. To check and set the optimum tyre pressure more accurately, you need to quickly develop your own chart of both pressure and temperature readings of the tyre “set”. This may be slightly different on the front and rear tyres and the off road camper trailer of caravan tyres. So you could end up with 3 sets of charts. You only need to do this once. You make your own chart by recording pressure and temperature and charting this. To do this you will need a TPMS (Tyre Pressure and Temperature Monitoring Systems). It will easily show you the readings and your “navigator” can record them as you drive. We will get to the optimum pressure in a further chapter... read on. kimberleygroup.com 9 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring) Is a screen based Tyre Pressure and Temperature Monitor a gimmick or another gadget for the driver? Some wives would say “yes” and yet it couldn’t be further from the truth. So here is the short version for the non technical followed by the long version for the passionate traveller. The main item Between you and the road are a set of Tyres. In fact when you turn the wheel to go around a corner, you turn the steel wheel and the tyre can try to “follow” your turn. If the tyre pressure is right, it will follow quickly, if not it may roll a little on the turn. If there is a little piece of recent tyre damage, this may open up on the turn creating a potential serious problem. The majority of serious road accidents in remote places that do not involve a second vehicle or animal are because of tyre failure. What can make your types doubly vulnerable is if they become excessively hot. With excessive heat, the Tyres are at their limit or beyond their operating conditions. A Tyre Pressure and Temperature Monitoring system does 2 things. The first is the obvious: if there is a dropping pressure the system goes into alarm once the pressure changes below a set point. The second is if the temperature rises above a set point. This is otherwise hard to measure and gives you an indication that the standard pressure you have set the Tyres at may not be optimum for the load, speed and ambient temperature. By adjusting your standard tyre pressure you can get optimum tyre wear without compromise to performance. Safety first, economy second. kimberleygroup.com 10 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring) Remember that the energy and forces at work with a vehicle and its trailer is proportional to the square of the vehicles speed. As you double your vehicles speed from say 40km/h to 80 km/h, the poten- tial energy in both the vehicle and the trailer moving around goes up FOUR (4) times. When approaching corrugations and difficult changes in road/track terrain, always reduce your speed. After sitting behind the wheel for several hours/day and several days, this is a difficult discipline to adhere to. Our guidelines are: You need 3 sets of tyre pressures to get the best out of both your tyres and camper trailer /off road caravan: 1. Higher pressures for vehicle stability at higher speeds; 2. Lower pressures to reduce ground pressure and gain greater traction in difficult ground. 3. Very low pressures for soft sand or thick mud This is Why a TPMS System and getting to the Optimum Tyre Pres- sure is crucial. The Tyre Pressures will change with: • The Speed you are travelling at, • The Load, • And the road conditions as indicated above. The Only thing you can change easily with these 3 parameters is your road speed. The TPMS will show you how your tyre pressures are changing with road conditions and speed.