Reading wheel markings

When building or customizing a motorcycle, you are dealing with two different sets of DNA: the markings stamped into the metal of your rim and the data molded into the sidewall of your tire. Understanding both is the only way to ensure your bike is safe and handles as it should.

Rim Markings

The stamps on your rim (usually found on the lip or between the spokes) tell you the physical specifications of the wheel.

Example: MT 3.50 J x 17 DOT

MT: Short for Motorcycle Tyre profile. This is a critical safety feature. MT rims feature "safety humps" that keep a tubeless tire bead locked in place if you lose air pressure.
3.50: The width of the rim bed in inches.
J: This letter describes the shape of the rim flange. J is the universal standard for modern street motorcycles.
17: The diameter of the wheel in inches.
DOT: This confirms the rim meets international safety standards.

Tire Markings

The sidewall of your tire contains its "passport." It tells you exactly what size it is, how it was built, and how old it is.

Example: 180/55 ZR 17 (73W)

180 (Width): The nominal width of the tire in millimeters.
55 (Aspect Ratio): The height of the sidewall as a percentage of the width. In this case, the height is 55% of 180mm.
ZR or R (Construction): This indicates the internal build. R stands for Radial. If you see ZR, it is a high speed radial tire rated for speeds above 240 km/h. B stands for Bias-belted, often used on heavier cruisers for stability.
17 (Diameter): The diameter in inches. This must always match your rim size exactly.
DOT Code (Production Date): Look for a four digit number in an oval. 5325 means the tire was made in week 53 of 2025. We recommend replacing tires older than 5 to 6 years, as rubber hardens over time.
Rotation Arrow: Most tires are directional. Mounting a tire backwards negatively affects water displacement and handling.
TL / TT: TL stands for Tubeless. TT is Tube Type. You can use a tube in a TL tire if your rim requires it, but never run a TT tire without a tube.
73W: These are the Load and Speed ratings, found in the tables below.

Load Index Table

The load index is a numerical code indicating the maximum weight a tire can carry at its maximum inflation pressure.

Index	Weight (kg)	Index	Weight (kg)	Index	Weight (kg)
21	82.5	44	160	67	307
22	85	45	165	68	315
23	87.5	46	170	69	325
24	90	47	175	70	335
25	92.5	48	180	71	345
26	95	49	185	72	355
27	97.5	50	190	73	365
28	100	51	195	74	375
29	103	52	200	75	387
30	106	53	206	76	400
31	109	54	212	77	412
32	112	55	218	78	425
33	115	56	224	79	437
34	118	57	230	80	450
35	121	58	236	81	462
36	125	59	243	82	475
37	128	60	250	83	487
38	132	61	257	84	500
39	136	62	265	85	515
40	140	63	272	86	530
41	145	64	280	87	545
42	150	65	290	88	560
43	155	66	300	89	580

Speed Rating Table

This letter indicates the maximum speed the tire is certified for under its maximum load.

Symbol	Max Speed (km/h)	Max Speed (mph)
J	100	62
K	110	68
L	120	75
M	130	81
N	140	87
P	150	93
Q	160	99
R	170	106
S	180	112
T	190	118
U	200	124
H	210	130
V	240	149
W	270	168
(W)	Above 270	Above 168

Workshop Wisdom

When you are building, precision is everything. A tire might physically fit a rim, but if the load index is too low for your machine or the production date is ancient, it is a safety hazard. Always check the MT hump on your rim before going tubeless. No hump means you must use a tube, no matter what the tire says.

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