Did you know that when you search for a specific tyre size on rezulteo, we also suggest tyres in compatible sizes with a different load index and/or speed rating? So, which sizes can be recommended, and which cannot? And are there any benefits to choosing tyres with a different load index and speed rating to your original tyres? Read on for all the details.

By Published On: 31 May 2021Categories: Legislation771 words3.9 min read
Rezulteo uses specific rules to suggest tyres compatible with your vehicle
Rezulteo uses specific rules to suggest tyres compatible with your vehicle © istock

What is an “approved” tyre size?

Car manufacturers assign one or more “approved” tyre sizes to their vehicles to ensure safety and compliance with legislation.

When buying tyres online or from your local garage, you may be offered tyres with a load index and speed rating that differ from the approved size, for example with a different letter (91V becomes 91W) or a higher number (91V becomes 94W).

Load index: what does it refer to?

The tyre load index is the last two numbers of the size: 205 55 R16 91W. This number refers to the maximum load the tyre can carry. With your load index, you can use the table below to find the maximum load of your tyres in kg.

Load index Weight in kg Load index Weight in kg
20 80 78 425
22 85 79 437
24 85 80 450
26 90 81 462
28 100 82 485
30 106 83 487
31 109 84 500
33 115 85 515
35 121 86 530
37 128 87 545
40 136 88 560
41 145 89 580
42 150 90 600
44 160 91 615
46 170 92 630
47 175 93 650
48 180 94 670
50 190 95 690
51 195 96 710
52 200 97 730
53 206 98 750
54 212 99 775
55 218 100 800
58 218 101 825
59 243 102 850
60 250 103 875
61 257 104 900
62 265 105 925
63 272 106 950
64 280 107 975
65 290 108 1000
66 300 109 1030
67 307 110 1060
68 315 111 1090
69 325 112 1120
70 335 113 1150
71 345 114 1180
72 355 115 1215
73 365 116 1250
74 375 117 1285
75 387 118 1320
76 400 119 1360
77 412 120 1400

Speed rating: what does it refer to?

The tyre speed rating or symbol is the letter at the end of the size: 205 55 R16 91W. This alphabetical code refers to the maximum theoretical speed at which the tyre can be driven.  With your speed rating, you can find the tyre’s maximum speed in km/h using the table below:

Rating maximum speed Rating maximum speed
J 100 km/h S 180 km/h
K 110 km/h T 190 km/h
L 120 km/h U 200 km/h
M 130 km/h H 210 km/h
N 140 km/h V 240 km/h
P 150 km/h W 270 km/h
Q 160 km/h Y 300 km/h
R 170 km/h ZR > 300 km/h

For more info, consult our guide “How to read tyre markings”

Why do we suggest alternative sizes?

At rezulteo, we want to help you buy tyres that fit your needs and ensure your safety, while complying with legal requirements. We therefore suggest approved tyre sizes which may have a different load index and speed rating to those originally fitted on your car. This allows you to have a greater choice of compatible tyres. 

What are the advantages for you?

  • you will have a wider selection of tyre choices that may allow you to find a cheaper price.
  • choosing a higher speed rating can potentially offer a sportier driving sensation.
  • choosing a lower speed rating for winter tyres is likely to improve traction on snowy surfaces.

What does the law say?

According to UK law, replacement tyres must have a load index suitable for your car when fully-loaded. They must also have a speed rating capable of meeting your vehicle’s maximum speed. 

When suggesting tyres in our comparison tool, rezulteo takes these points into account and may in some cases suggest tyres with a different load or speed index from your initial request but which are compatible in terms of legal and safety requirements.

What rules are applied to your tyre search?

rezulteo recommends products in accordance with current legislation and our own recommendations. Which tyres appear in your search results is decided according to the following rules: 

If you search for summer tyres in a manufacturer-approved size

Results include:

  • summer tyres in the exact size searched for
  • summer tyres with a higher load index and/or higher speed rating

=> For example, if you search for 205 55 R16 91 V.

Results include tyres in:

  • 205 55 R16 91V
  • 205 55 R16 91W
  • 205 55 R16 94V
  • 205 55 R16 94W

If you search for winter tyres in a manufacturer-approved size.

Results include:

  • winter tyres in the size recommended by your manufacturer
  • winter tyres with a speed rating up to two ratings lower than the original

=> For example, if you search for 205 55 R16 91 W.

Results include tyres in:

  • 205 55 R16 91 W
  • 205 55 R16 91 V
  • 205 55 R16 91 H
“on winter tyres: rezulteo can recommend tyres with a maximum or two ratings lower than the size recommended by your manufacturer down to a minimum of Q”
  • 205 55 R16 91U

In the event of non-compliance with recommended sizes …

By ignoring the above recommendations concerning the load index and speed rating approved for or compatible with your vehicle, you risk:

  • a fine during a roadside police check
  • an MOT retest
  • not being covered by your insurance in the event of an accident
  • premature and abnormal tyre wear
  • reduced performance and safety of your vehicle
  • endangering other vehicles and passengers

Consult our guide “2 options to change your tyre size without being fined”

Conclusion: how does rezulteo recommend sizes?

When searching for a tyre, the rezulteo website displays recommendations depending on the size entered, the season and the previously mentioned rules. The comparison table presents a list of tyres in sizes compatible with your vehicle.  Tyres with a different load index and/or speed rating to the original size are displayed with an exclamation mark.

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