Michelin Tyre Sizes & Load Indexes.pdf

Tyre sizes and designations
Tyre sizes are indicated by a combination of letters and numbers. The most common format is the "R" format, which includes the tyre width, aspect ratio, and load index. The "R" format is used for radial tyres, which are the most common type of tyre.

The tyre width is indicated in millimeters, and the aspect ratio is a percentage that indicates the ratio of the tyre's width to its diameter. The load index is a number that indicates the maximum load that the tyre can support.

For example, a tyre with the size 205/70 VR 15 has a width of 205 millimeters, an aspect ratio of 70%, and a load index of VR. The "VR" speed code indicates that the tyre is designed for speeds up to 210 km/h.

Tyre sizes can also be indicated by a combination of letters and numbers, such as 1245, which indicates a tyre with a width of 12 inches and an aspect ratio of 45%.

Load indexes and speed codes
Most tyres include indications for use, such as the load index (number) and speed code (letter). The load index indicates the maximum load per tyre, while the speed code indicates the maximum authorized speed of use.

Load indexes range from 62 to 120, with higher numbers indicating higher loads. Speed codes include letters such as H, V, W, and Y, which indicate different speed ranges.

Tube type and tubeless
Tyres can be either tube type or tubeless. Tube type tyres have an inner tube separate from the tyre, while tubeless tyres have an inner tube incorporated into the tyre.

It is advisable to fit new Michelin tubes into new Michelin tube type tyres and also in tubeless tyres if the wheel is not suitable for tubeless fitments. The tube should always be lightly coated with French chalk and inflated slowly to avoid trapping air between the tyre and the tube.

Tyre sizes and designations
Michelin offers a range of tyres for classic cars, including Cross-ply tyres with bead wires and conventional tyres. The tyre sizes and designations for these tyres are as follows:

Cross-ply tyres with bead wires
The Double Rivet and Superconfort tyres are two products in the Cross-ply tyre category with bead wires. The Double Rivet tyre has a tread that was created with the first generation of car tyres, beaded edge tyres. The Superconfort tyre was launched in 1932 and offered a very low-pressure tyre with much slower wear.

Conventional tyres
The conventional tyres offered by Michelin include the SCSS, DR, and Ret tyres. The SCSS tyre has a seat dimension of 130/140 - 40, a tread cross-section width of 40 mm, and an external diameter of 130 mm. The DR tyre has a seat dimension of 165, a tread cross-section width of 2150 mm, and an external diameter of 722 mm.

Inflation pressures for conventional tyres
The inflation pressures for conventional tyres are as follows:

2b: 2 bar, load 40 kg
2.5b: 2.5 bar, load 50 kg
3.0b: 3 bar, load 60 kg
3.5b: 3.5 bar, load 70 kg

The tyre sizes and designations for the conventional tyres are as follows:

130/140 - 40: SCSS
165: DR
175: DR
194: DR
193: DR
2367: DR
566: DR
677: DR
783: DR
668: DR
143: DR
730: DR
2175: DR
328: DR
392: DR
453: DR
513: DR
18 C Ret: DR
149: DR
740: DR
2205: DR
347: DR
415: DR
480: DR
543: DR
18 C Ret: DR
154: DR
740: DR
2205: DR
356: DR
426: DR
493: DR
557: DR
18 C Ret: DR
184: DR
799: DR
2382: DR
511: DR
610: DR
706: DR
797: DR
18 C Ret: DR
147: DR
745: DR
2160: DR
331: DR
396: DR
458: DR
513: DR
17/18 E Ret: DR
156: DR
762: DR
2290: DR
425: DR
508: DR
587: DR
660: DR
17/18 E Ret: DR
178: DR
798: DR
2362: DR
511: DR
610: DR
706: DR
797: DR
17/18 H Ret: DR
128: DR
738: DR
2214: DR
283: DR
338: DR
391: DR
422: DR
18/19 CD Ret or 19 UHD: DR
141: DR
766: DR
2304: DR
353: DR
422: DR
489: DR
550: DR
18/19 CD Ret or 19 UHD: DR
168: DR
807: DR
2400: DR
444: DR
531: DR
614: DR
708: DR
19/20 H Ret or 20 H: DR
194: DR
866: DR
2550: DR
585: DR
700: DR
810: DR
916: DR
19/20 H Ret or 20 H: DR
21: DR
5,50/7,00 - 20: DR
194: DR
866: DR
2550: DR
585: DR
700: DR
810: DR
916: DR