How to Optimize your Tyre Pressures and Temperatures on your Caravan/Camper and

Transcription

1 How to Optimize your Tyre Pressures and Temperatures on your Caravan/Camper and insert image here: your 150 x 80mm vehicle

2 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

3 3 Importance of Optimum Tyre Pressure and Temperature This ebook addresses the question: How much of Australia do you want to experience?

4 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.

5 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 temperature. Changes in the ambient air temperature 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!

6 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.

7 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.

8 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.

9 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.

10 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 potential 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 Pressure 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.

11 11 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring) Travelling at high speed (100km/hr +) on black tarmac or well graded dirt roads requires good vehicle and trailer stability. The greater energy in either your vehicle or trailer at high speed puts lateral forces on the wheels and therefore tyres in cornering and overtaking manoeuvres. In the end, the tyres take these forces. The lower the tyre pressure, the more the tyres will compress and change shape under these forces. Therefore keep the tyre pressure high. Decreasing tyre pressure increases the tyre footprint. This reduces the pressure on the ground for better floatation. It also improves traction on difficult terrain. However, the lower tyre pressure for a given speed/load will increase the tyre wall temperature. The higher the tyre wall temperature makes the tyres more vulnerable to failure/punctures. The best variable to control here is SPEED. If you lower the maximum speed the tyre temperature rise should be acceptable. Tyre pressures should raise approx 5% for every 10 degrees Celsius increase in operating temperature. If there is a 20 degree increase from cold to hot, there will be a 10% increase in pressure. (5% is close to 1 psi in most cases) Do NOT exceed the maximum tyre pressure especially when the tyres are hot as published by the manufacturer and shown on the tyre. A good quality accurate tyre pressure gauge or a TPM System is essential do not rely on those in the inflation hoses in petrol stations!

12 12 Importance of Optimum Tyre Pressure and Temperature Monitor your speed as well as pressure/ temperature In this scenario: You are travelling on dirt/difficult roads You set the tyres pressures low. You start off restricting your speed but after a while, the road improves you want to increase your speed If you want to increase your speed, YOU MUST monitor your tyre pressures and temperatures. Depending on conditions you may have to increase your tyre pressures. If you are using a TPMS, you can monitor and optimize this without having to get out and keep checking! You can work to a 4PSI rule or 6 PSI rule depending on road conditions. Over time you will establish with a TPMS the best Tyre Pressure/ temperature settings for your rig.

13 13 Importance of Optimum Tyre Pressure and Temperature Suggested Pressures and Speed for conditions Tyre Example used is BFG 265/75 R16 120Q Rating 1400kgs Max 160k/hr Max Axle Load 1800 kgs Axle 900 kgs Wheel/Tyre 1600 kgs Axle 800 kgs Wheel/Tyre 1400 kgs Axle 700 kgs Wheel/Tyre 1200 kgs Axle 600 kgs Wheel/Tyre Hard Black Road Limit of 100k/hr 3.4 bar 49 psi 2.8 bar 40 psi 2.4 bar 35 psi 1.9 bar 27 psi Gibber Roads and Tracks or thin mud Suggest Limit of 65k/hr 2.3 bar 33 psi 1.9 bar 27 psi 1.6 bar 23 psi 1.3 bar 19 psi Soft sand or thick mud Suggest Limit of 20k/hr 1.2 bar 17 psi 0.9 bar 13 psi 0.7 bar 10psi 0.6 bar 9 psi WARNING: This table is a guide. Local conditions, the load in your unit and the behaviour of your vehicle under different loads will change the way it handles. Control your speed at all times especially in difficult or unknown conditions These Pressures are for COLD approx 15 C Temperatures For every 10 C temperature rise, increase desired temperature by 5% or approx 1psi.

14 14 Importance of Optimum Tyre Pressure and Temperature Conversion Table Bar PSI Bar PSI

15 15 Importance of Optimum Tyre Pressure and Temperature Is there an optimum size tyre? To minimise pressure increases, tyre engineers work on every one of the 200 ingredients that go into each high quality tyre. The development of a tyre is consequently a very lengthy and complex process as it is matched to the application. How wide should a Tyre be? Does wider provide better grip? If the load is the same, the contact patch with the ground will be the same for a given tyre pressure regardless of the width of the tyre. A wide tyre will therfore have a shorter length of oval patch in contact with the ground than a narrower tyre at the same pressure. In dry conditions this is good, but in wet conditions, a longer oval patch in the direction of travel may enhance road holding in wet conditions. (The contact patch is really a squashed oval rather than a rectangle) The area of the contact patch does not affect the actual grip of the tyre. The things that do affect grip are the coefficient of friction and the load on the tyre - (tyre load sensitivity). Rubber friction is broken into two primary components - adhesion and deformation or mechanical keying. Rubber has a natural adhesive property and high elasticity which allows it readily deform and fill the microscopic irregularities on the surface of any road. This has the effect of bonding to various surfaces, which aids in dry weather grip but is diminished in wet road conditions. Changing the Tyre Pressure will therefore not significantly change the grip of the tyre in different conditions. It is the load on the tyre and the forces associated with speed.

16 16 Importance of Optimum Tyre Pressure and Temperature Acceleration, Braking and Load Transfer During acceleration or braking grip is reduced partly from the change is suspension geometry and party from the transfer of load from one set of tires to another. Since the coefficient of friction is changing (lower for higher loads), the net grip during acceleration is reduced. In other words maximum grip occurs when all four tires are loaded equally. In reality the contact patch is effectively spinning around your tyre at some horrendous speed. When you brake or corner, load-transfer happens and all the tyres start to behave differently to each other. This is why weight transfer makes such a difference the handling dynamics of the car. In braking for instance; weight moves forward, so load on the front tyres increases. The reverse happens to the rear at the same time, creating a car which can oversteer at the drop of a hat. If the load-transfer shift because of a connected carvan or trailer was suddenly unbalanced, a rapid left-right-left on the steering wheel would upset the load so much that the vehicle lost grip in the rear, went sideways, jack-knifed and rolled over. There is a complete ebook on Towing Stability that has much more information on all the parameters that contribute to safe towing.

17 17 Importance of Optimum Tyre Pressure and Temperature Specifications of TPMS 1. SENSOR AND TRANSMITTER SPECIFICATIONS Battery life More than 7 years, nominal. Storage temperature -40oC to 125oC Operating temperature -30oC to 120oC Operating humidity 95% Operating frequency MHz Pressure monitoring range 0~87 psi Pressure reading accuracy At Normal condition ± 1psi at normal pressure range Temperature reading accuracy ± 4oC in normal environmental condition Transmission power Max 5 dbm Battery 3.0V Sensor weight 32g ±3g 2. RECEIVER SPECIFICATIONS Operating voltage 12V DC Operating current < 200mA Monitored temperature range -30oC to 105oC Operating temperature -30oC to 85oC

18 18 Importance of Optimum Tyre Pressure and Temperature TPMS Kits (Showing only 4 Sensors instead of 8 or 12 sensors depending on Kimberley Model)

19 19 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes If you take time to look at the side wall of your tyres, whether they be on your 4WD vehicle, caravan, camper trailer, you will find a great deal of important information. Each tyre will have distinct markings. Light truck (L/T) tyres are often used on 4WD vehicles, caravans, Terms: LT for light truck tyres. P = passenger car tyre ST for Special Trailer tyre 205 = (width) is the metric measurement across the widest portion of the sidewall (section width) in millimeters. / = The slash is the mathematical term indicating ratio. 65 = (height of side wall) the mathematical result of dividing the section height (depth of the tyre cross-section from the tread to the bead) by the section width (see above). This may also be referred to as the profile or series of the tyre. Eg: low profile or 70 series tyre. Ratios approaching 1 are generally associated with high carrying capacity and lower speed while low ratio.70 to.35 generally are towards a high performance capability with high speed and handling quality. In this case, the tyre height is approx 75% of the tyre width.

20 20 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes R = an alphabetical term for a radial tyre. In a radial tyre the cords run perpendicular to the bead of the tyre directly across the crown to the opposite bead. 16 = (rim diameter) this numerical number is the diameter of the bead of the tyre in inches. Bead seat diameters are manufactured in ½ inch increments. This tyre is designed to fit a wheel with a 16 inch diameter. 95 V = load/speed index (see load range below). A speed designation at which the tyre can carry the load corresponding to the Load Capacity Index. AT: All Terrain M = meets the Rubber Manufacturer s Association standards for a mud tyre. These can also be recorded as combinations such as M/T for Mud Terrain. Speed Symbol Maximum Speed (km/ph) L 120 M 130 N 140 P 150 Q 160 R 170 S 180 T 190 U 200 H 210 V 240 Z 240 W 270 Y 300 LR is the load range and the D is the defined carrying capacity. The higher the letter in the alphabet, the higher the carrying capacity. The load range codes relates to the old system of plies. For example, D is the 4th letter of the alphabet and multiply it by 2 (4 x 2 = 8) or 8 ply rated tyre. (Another example is E which is the 5th letter of the alphabet (5 x 2 = 10) or 10 ply). This shows us that the more carrying capacity we need the higher load range we require. Load Range (LR) D = (8 ply rating) is the load carrying capacity of the tyre. (eg: D = Load Index 110, E = Load Index 116) Max Load Single 1380 kg ( kp3 (65 PSI) COLD Max Load Dual 1260 kg ( kp3 (65 PSI) COLD

21 21 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes Tyre Maximum Load Rating contd. Max Load = the maximum load capacity of the tyre. Operating a tyre over its rated capacity may damage the tyre internally. Single = is the stated capacity when the tyre is installed in a single tyre application ie: one tyre on each end of an axle lbs = rated carrying capacity of the tyre in pounds when installed in a single configuration. 65PSI = the minimum air pressure required to obtain the carrying capacity of 3042 lbs. If you reduce the inflation pressure the rated carrying capacity decreases. (Tyre pressure is measured in kilopascals (kpa) or pounds per squar inch (psi)). COLD = this is the inflation pressure of the tyre cold, that is the tyre temperature before you commence a journey. Tubeless = has no rubber tube. The tyre seals on the rim via the bead and it has an external valve Treadplies = rubber coated cords forming the footprint of the tyre Polyester cord = a synthetic fibre that maintains strength properties at high heat levels and eliminates flat spotting. Tyre Load Rating Index Number Maximum Permissible Load (kg)

22 22 Importance of Optimum Tyre Pressure and Temperature Tyre Ageing Even unused tyres perish over time especially those exposed to heat, sunshine (UV radiation) and salt spray. Tyres are marked with the production date of the tyre and understanding these marking can help you determine the age of a tyre. Spare tyres fitted to caravans, motorhomes, fifth wheelers and trailers are often exposed to the elements and can age prematurely. It is recommended that you do not use tyres more than 6 years old from the date of manufacture. If a tyre has been in use, it has been reported that the effect of ageing has been lessened to a degree, but depending on the wear they should be replaced before 10 years. If you are in any doubt about the age and wear of a tyre discuss it with a tyre expert or replace it. How do I tell the age of a tyre? Tyres carry a DOT (USA Dept of Transport) number on the sidewall that gives a production date. Since the year 2000 the numbers consist of 4 digits instead of 3. The first two digits indicate the calendar week of production and the next two the year of production. Eg: 3004 the tyre was manufactured in the 30th week of 2004.

23 2 ebook Summary Conclusion & Additional Resources Overall Design ebooks Off-road Soul, Independent Spirit. A Design Guide to insert image here: Sustainability with 150 x 80mm off-road caravans

24 3 ebook Summary Energy and Satellite ebooks Copyright Kimberley Kampers Pty Ltd

25 4 ebook Summary Boating, Tyres ebooks How to Optimize your Tyre Pressures and Temperatures on your Caravan/Camper and insert image here: 150 x 80mm your vehicle Copyright Kimberley Kampers Pty Ltd

26 5 ebook Summary Multi-Media and Digital Photography ebooks Getting the most from Multi-Media in insert image here: Off-road 150 x 80mm Camper Trailers Coming Soon Digital Photography Paks For off road campers, caravans and Full Size off road caravans. Easiest way to operate, written by an off-road photographer Copyright Kimberley Kampers Pty Ltd

27 6 ebook Summary Test Data, calculators online Pricing Guided Solar Calculator on website: New Kimberley online Configuration and Pricing System coming 1st Quarter 2013 Copyright Kimberley Kampers Pty Ltd