Must Read Guide to Tyre Safety Measures

1. MUST READ GUIDE TO TYRE SAFETY MEASURES Published by MOT Llandudno

2. INTRODUCTION

3. The majority of us understand the basics of tyre safety, so why do we wait until our MOT to be told we need new tyres? According to the Driver and Vehicle Standards Agency (DVSA), between April 2015 and March 2016, over 2 million class 3 and 4 vehicles (cars and light vans up to 3,000 kg) failed their MOT due to defective tyres. Dangerous and illegal tyres account for one in four MOT failures. As the only point of contact with the road, it is important to understand how the condition of your tyres can affect your vehicles safety and its performance.

4. Having over or under inflated tyres, even by one bar, can reduce a cars fuel efficiency and it is estimated that British motorists may be unnecessarily spending up to £600 million on fuel because of incorrect tyre pressures. In addition to reduced fuel efficiency, having incorrect tyre pressure may reduce the longevity of your tyres. It can also affect your cars road handling, increase the vehicles stopping distance and consequentially, the likelihood of being involved in a road traffic accident is greater.

5. STOPPING DISTANCES

6. The distance your vehicle takes to stop will depend on your attention, weather conditions, the road surface, your vehicle and the condition of its tyres. Typical stopping distances, as published by the Highway Code are as follows:

7. In wet weather, stopping distances are doubled, in icy conditions they are multiplied by 10. If your tyres are worn to their legal limit of 1.6mm, your vehicles stopping distance can be increased by as much as 60%. Shockingly, statistics compiled by The Department for Transport (2014) reveal that, where vehicle defects were a contributory factor to reported fatal road accidents, 56% were due to illegal, defective or under inflated tyres. If these statistics alone aren’t enough to get you running outside to check your tyres, then we don’t know what is but, if you’re unsure of what to check for, we’ve devised this useful tyre safety guide, so you don’t have to become statistic!

8. TYRE TREAD DEPTH

9. The legal requirement for a tyre tread depth is a minimum of 1.6mm across the central three-quarters of the tyre. The tread must meet this requirement around the tyres’ entire circumference. Checking your tyre tread depth is a task you should perform regularly. Follow our simple techniques for a quick and pain free solution:

10. TYRE TREAD WEAR INDICATORS Most tyre manufacturers now produce tyres with tread wear indicators. These are small, raised ‘nodes’ that are evenly spaced around the circumference of the tyre, within the main tread grooves. If the tyre has worn to a point that the ‘node’ is flush with the outer tread, it means the tyre is below its legal limit and needs replacing.

11. As you can imagine, this test involves using a 20p coin. Simply place the coin in the main tread grooves of the tyre. If the tyre is above the legal limit, the outer band of the 20p will be hidden from view, within the tread of the tyre. If the outer band is visible, the tread depth may be illegal and the tyre may need replacing. It is important to check several locations on each tyre as they can wear unevenly, particularly if the pressure is incorrect. THE 20P TEST Source: https://www.tyresafe.org/tyre-safety/tread-depth/

12. Tyre depth gauges offer a quick and simple method of checking the thread depth of your tyres. There are variations in price depending on the sophistication of the model you choose. A manual gauge can be picked-up for under £1 or, if you’re a gadget type of person, a digital gauge (many include a tyre pressure checker) can set you back about £10. Either device will give you a good indication as to how legal the tread depth is on your tyres. BUY A GADGET

13. TREAD PATTERN WEAR

14. How the tread pattern of your tyre is wearing is a good indication as to the overall health of your vehicles suspension components, the alignment of your wheels and if the tyres are under or over inflated. Abnormal tyre wear can occur for a number of different reasons, below are examples of the most common problems to look out for:

15. Tyres with insufficient air will wear more quickly on the outer edges compared to the central area of the tyre. Under inflation causes a dip in the centre of the tyre meaning the outer edge, and potentially the wheel rim, are more susceptible to damage. UNDERINFLATED TYRES

16. The centre of the tyre tread will appear more worn if your tyres have too much air. Overinflating causes the tyre to bulge in the middle, meaning there is less surface area in contact with the road, which not only makes for an uncomfortable ride but also reduces grip. OVERINFLATED TYRES

17. You should check your tyre pressures regularly to ensure they meet the manufacturers guidelines. The correct tyre pressures for your car can be found in your vehicle handbook, inside the fuel filler cap or on the driver’s door sill. Alternatively, TyreSafe have devised a useful tyre pressure checker on their website, all you need is your car make and model. It’s also worth noting, when shifting heavy loads, your tyre pressure will need increasing, recommended settings can be found in your vehicle handbook.

18. These are the angles of the wheels; camber is the lean of the wheel away from the vehicle when viewed from the front, toe is the direction the tyres point relative to the centre of the vehicle. If the tyres are excessively worn on the outer edge, positive camber and/or toe-in are the likely suspects. If the tread is worn on the inside edge of the tyre then negative camber and/ or toe-out is the issue. With toe-in and toe-out you may also feel a feathered effect when running your hand along the tread. CAMBER AND TOE

19. If you suspect your car is suffering from a camber and/or toe problem, don’t panic, a simple wheel alignment by a reputable garage should fix the issue. Misalignment can happen when we accidently hit a kerb, drive through a pothole, or it could be the result of worn suspension components, whatever the reason, it’s definitely worth getting it checked out.

20. If you notice cups or dips around the edge of the tread, or if you experience a tyre wobble or vibration when driving over 40-50 mph, one or more of your tyres could be out of balance with the others. BALANCE

21. Wheel balancing is a straightforward job for any reputable garage. The technician will place small weights at specific points around the edge of the wheel to ensure that the weight of the wheel and tyre is even around the axis. If a re-balance doesn’t fix the issue, then the problem could be more serious, such as weakened struts or shock-absorbers, your garage will be able to advise.

22. CONDITION

23. Stones and grit can be troublesome for tyres. If debris becomes embedded in the tread, it can work its way into the casing of the tyre and result in a puncture. Remove all debris and if you suspect any damage, no matter how small, it’s advisable to get the tyre checked by a specialist. DEBRIS

24. Potholes, speed bumps and kerbs can damage the structural integrity of the tyre sidewall. If the sidewall becomes weakened, air leaks from inside the tyre through to the carcass creating a visible lump or bulge. If you find a lump or bulge in your tyre sidewall, it is unlikely that it will be repairable so expect to have to replace the tyre. LUMPS AND BULGES

25. A tear, cut or crack in your tyre doesn’t necessarily mean it has to be replaced. In some cases, depending on the severity, a repair can be carried out. This type of damage is often caused by that pesky debris, or it may be just plain old age weakening the rubber. When inspecting for tears, cuts and cracks make sure to check between the tread grooves. If you discover nylon cords poking through any damage on the tyre, the internal structure may have been compromised so DO NOT drive the vehicle without first changing the tyre. TEARS, CUTS AND CRACKS

26. The lifespan of a tyre cannot be determined by a single factor. Heat, storage and the conditions of use all influence how tyres age but if your tyres are approaching five years old, it’s advisable to keep close eye on their condition and consider replacing them. To identify the date your tyre was manufactured, and establish its age, a four-digit code is imprinted on the tyre sidewall. Sometimes proceeded by ‘DOT’, the first two digits of the date stamp represent the week of manufacture and the second two digits signify the year of production. The tyre below was made in the 6th week of 2013.

27. DATE OF TYRE MANUFACTURE Source: https://aston1936.com/2016/01/15/inspecting-the-tires-on-an-aston-martin-db9/

28. Signs of damage to a tyre, such as lumps, bulges, tears, cuts or cracks can be extremely dangerous and may put you at risk from a tyre blowout. If you are in any doubt contact a tyre specialist. 


29. TYRE SIZE

30. The size of your tyres must be in accordance to your vehicle manufacturers handbook. The handbook may specify a different size for the front and rear, but tyres fitted to the same axel must be of the same size. Once you know the correct tyre size for your vehicle, check this matches the size currently fitted, the tyre size will be printed on the sidewall of your tyres. Fitting an incorrect tyre size can result in an MOT failure!


31. TYRE MARKINGS

32. This is displayed in millimetres so for our tyre above marked 195, the measurement across the tread from sidewall to sidewall will be 195mm. WIDTH

33. Also known as the aspect ratio, this is the height of the tyre sidewall, expressed as a percentage of the tyre width. For our tyre above its 55, meaning that the profile height of the tyre is 55% of its width. PROFILE

34. These two digits represent the size of the wheel rim that a tyre can be fitted to. For our example, the rim diameter is 16, so this tyre will fit on a 16-inch wheel rim. RIM DIAMETER

35. Load Per Tyre (KG) Load Per Tyre (KG) Load Per Tyre (KG) Load Per Tyre (KG) Load Per Tyre (KG) Load Index Load Index Load Index Load Index Load Index         62 265   75 387   88 560   101 825   114 1180 LOAD INDEX 63 272   76 400   89 580   102 850   115 1215 64 280   77 412   90 600   103 875   116 1250 65 290   78 425   91 615   104 900   117 1285 66 300   79 437   92 630   105 925   118 1320 67 307   80 450   93 650   106 950   119 1360 68 315   81 462   94 670   107 975   120 1400 69 325   82 475   95 690   108 1000   121 1450 70 335   83 487   96 710   109 1030   122 1500 71 345   84 500   97 730   110 1060   123 1550 72 355   85 515   98 750   111 1090   124 1600 73 365   86 530   99 775   112 1120   125 1650 74 375   87 545   100 800   113 1150   126 1700

36. Speed Rating Miles Per Hour Kilometres Per Hour TYRE SPEED RATING N 87 140 P 93 150 Q 99 160 R 106 170 S 112 180 T 118 190 U 124 200 H 130 210 V 149 240 Z 150+ 240+ W 168 270 Y 186 300

37. CONDITION

38. Legally, tyres of the same construction must be fitted to the same axel. There are two basic types of tyre construction; radial and cross-ply, each has its own unique set of characteristics:

39. Invented by Michelin in 1946, the construction of a radial tyre allows the tread and sidewall to act independently, giving flexibility, strength and greater control over the direction of travel. The majority of tyres manufactured today are of radial construction. RADIAL

40. Generally, cross-ply tyres are only used on vehicles that work in extreme terrain as they have a rigid sidewall construction which protects against sidewall punctures from tree stumps or sharp rocks. A cross- ply tyre has a relatively low speed rating, meaning if you are travelling at motorway speeds over a period of time, you could experience a blow-out. 
 CROSS-PLY

41. The construction of your tyres can be determined by the printing on the sidewall. If there is an ‘R’ between the profile and rim diameter (as shown in the diagram above), the tyre will be of radial construction, if there is a – between these two elements, the tyre will be of cross-ply construction.

42. THE MOT

43. During an MOT, tyres and wheels will be inspected to check for the type of structure, the overall condition of the tyre, the size and the tread – pattern, breadth and depth. Spare wheels and tyres are not checked during the MOT process unless they are fitted to the vehicle. If, at the time of MOT, for some reason you have a ‘temporary use’ wheel fitted to your vehicle, the MOT test will be failed. Vehicles first used on or after 1st January 2012 will also have their Tyre Pressure Monitoring System (TPMS) checked during the MOT to make sure it is still working. Your vehicle will fail its MOT if a TPMS warning light is displayed on the dashboard at the time of testing.

44. TYRE PRESSURE MONITORING SYSTEM

45. The TPMS is a safety feature that automatically measures the pressure and, in some cases, the temperature of your tyres. There are two types of TPMS:

46. This type does not have physical air pressure sensors but detects low tyre pressure through the wheel speed sensors of the vehicles Anti- lock Braking System. When a tyre is low on pressure, its rotational speed increases and it is this difference between the rotational speed of each individual tyre that the indirect TPMS system recognises. If your tyres are all equally deflated, the indirect TPMS will not detect any difference between each tyres rate of revolution so you will not be alerted to an under-inflation problem. An indirect TPMS also requires the vehicle to be driven before an issue can be detected. INDIRECT TPMS

47. Within each tyre is a pressure monitoring sensor that is able to detect any changes in individual tyre pressure levels. A direct TPMS may also provide tyre temperature readings. This type of system tends to be more accurate than an indirect TPMS as it collects data straight from the tyre valves. Cars manufactured after 2014 will generally have a direct TPMS fitted. DIRECT TPMS

48. THE
 LEGAL STUFF

49. If caught with defective tyres you could face a fine of up to £2,500 per tyre. If all four tyres contravene regulations, you could be slapped with an enormous £10,000 bill. You will also be rewarded for your defective tyres with 3 penalty points that will stay on your driving record for 4 years from the date of offence. Now you know how important tyre safety is, please don’t leave it to chance or until your MOT, get out there and get checking.