Tire Size Calculator

Enter tire size (e.g., 265-70R17):

-R

Calculator Size Tools of Tire Size Calculator

How to use Tire Size Calculator tools?

Follow these step-by-step instructions to get the information you need:

1.Locate Your Current Tire Size:

Check the sidewall of your current tires to find the size printed on them. It will look something like this: 265-70R17. This number includes the tire width, aspect ratio, and rim diameter.

2.Input Your Current Tire Size:

In the calculator, enter the following details:

Width: The first number (e.g., 265).

Aspect Ratio: The second number (e.g., 70).

Rim Diameter: The last number (e.g., 17).

3.Click "Tire Size Calculate"

Once you've entered your tire size, click the button to calculate. This will process your input and display the recommended tire sizes.

What do the numbers in a tire size mean?

For example, in a tire size 265-70R17:

265 is the width of the tire in millimeters
70 is the aspect ratio (height of the tire's cross-section to its width)
R means it's a radial tire
17 is the wheel diameter in inches

Why is tire size important?

Tire size affects your vehicle's performance, fuel efficiency, and safety. The right size ensures proper fit and function.

How does changing tire size affect my vehicle?

Changing tire size can impact your speedometer accuracy, ground clearance, and overall driving characteristics. For instance, moving from a smaller size to 265-70R17 might increase your vehicle's ground clearance and alter its handling. Always consult your vehicle's manual or a professional before changing tire sizes.

What is the significance of revolutions per mile?

Revolutions per mile indicates how many times a tire rotates in one mile. This affects your vehicle's gearing, speedometer reading, and overall performance. A 265-70R17 tire will typically have fewer revolutions per mile compared to smaller sizes, which can affect your speedometer reading if not properly calibrated.

More Information about Tire Size

Aspect Ratio

Definition: The aspect ratio is the ratio of the tire's height to its width, expressed as a percentage. For example, in the tire size 265-70R17, the "70" indicates that the height of the tire is 70% of its width (265 mm).

Impact: A lower aspect ratio (e.g., 50) generally indicates a shorter sidewall, which can improve handling and stability at high speeds. However, it may result in a harsher ride over bumps. A higher aspect ratio (e.g., 70) offers more cushioning and comfort but may compromise handling slightly.

Aspect Ratio Comparison Table

Aspect Ratio	Sidewall Height	Characteristics
30-50	Low Profile	Better handling, less comfortable ride, more susceptible to rim damage
55-65	Mid Profile	Balance between handling and comfort
70-80	High Profile	More comfortable ride, better for off-road, slightly less responsive handling

Load Index / Load Chart

Definition: The load index indicates the maximum weight a tire can support when properly inflated. It is often found next to the tire size on the sidewall.

Impact: Choosing a tire with an appropriate load index is crucial for safety and performance. Using a tire with a lower load index than required can lead to tire failure or decreased handling.

Load Index Table (1-150) / Load Chart Table (1-150)

Load Index	Max Load (kg)	Max Load (lbs)	Load Index	Max Load (kg)	Max Load (lbs)	Load Index	Max Load (kg)	Max Load (lbs)
1	46	102	51	195	431	101	824	1816
2	48	105	52	201	443	102	848	1869
3	49	108	53	207	456	103	872	1923
4	50	111	54	213	469	104	898	1979
5	52	115	55	219	483	105	924	2037
6	53	118	56	226	497	106	951	2097
7	55	121	57	232	512	107	979	2158
8	57	125	58	239	527	108	1007	2221
9	58	129	59	246	542	109	1037	2286
10	60	132	60	253	558	110	1067	2352
11	62	136	61	260	574	111	1098	2421
12	64	140	62	268	591	112	1130	2492
13	65	144	63	276	608	113	1163	2565
14	67	148	64	284	626	114	1197	2639
15	69	153	65	292	644	115	1232	2717
16	71	157	66	301	663	116	1268	2796
17	73	162	67	310	682	117	1305	2878
18	76	167	68	319	702	118	1343	2962
19	78	171	69	328	723	119	1383	3048
20	80	176	70	337	744	120	1423	3137
21	82	182	71	347	766	121	1464	3229
22	85	187	72	357	788	122	1507	3323
23	87	192	73	368	811	123	1551	3420
24	90	198	74	379	835	124	1597	3520
25	92	204	75	390	859	125	1643	3623
26	95	210	76	401	884	126	1691	3728
27	98	216	77	413	910	127	1741	3837
28	101	222	78	425	937	128	1791	3949
29	104	229	79	437	964	129	1844	4065
30	107	235	80	450	992	130	1898	4183
31	110	242	81	463	1021	131	1953	4305
32	113	249	82	477	1051	132	2010	4431
33	116	256	83	491	1082	133	2069	4561
34	120	264	84	505	1113	134	2129	4694
35	123	272	85	520	1146	135	2191	4831
36	127	280	86	535	1179	136	2255	4972
37	131	288	87	550	1213	137	2321	5117
38	134	296	88	566	1249	138	2389	5266
39	138	305	89	583	1285	139	2459	5420
40	142	314	90	600	1323	140	2530	5578
41	146	323	91	618	1362	141	2604	5741
42	151	332	92	636	1401	142	2680	5909
43	155	342	93	654	1442	143	2759	6082
44	160	352	94	673	1484	144	2839	6259
45	164	362	95	693	1528	145	2922	6442
46	169	373	96	713	1572	146	3007	6630
47	174	384	97	734	1618	147	3095	6824
48	179	395	98	755	1665	148	3186	7023
49	184	406	99	777	1714	149	3279	7228
50	190	418	100	800	1764	150	3374	7439

Note: This table shows load indexes from 1 to 150. The load capacity increases by approximately 2.92% for each increment in the load index.

Speed Rating

Definition: The speed rating is a letter that indicates the maximum speed a tire can safely maintain over time. Common ratings include P (up to 93 mph), Q (up to 99 mph), and Z (over 149 mph).

Impact: Selecting a tire with a suitable speed rating is essential for safe driving, especially if you drive at higher speeds. Using a tire with a lower rating than your vehicle's capabilities can increase the risk of blowouts.

Speed Rating Table

Speed Symbol	Max Speed (km/h)	Max Speed (mph)
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
Y	300	186
(Y)	300+	186+

Note: '(Y)' indicates speeds over 300 km/h (186 mph) where the exact maximum speed should be specified by the tire manufacturer.

Considerations When Changing Tire/Wheel Size

Changing tire or wheel size can be motivated by various factors, often including aesthetic preferences. However, it's crucial to take several considerations into account to avoid potential negative consequences, such as increased wear on the vehicle's suspension and brake components (especially anti-lock brakes), which can affect handling and lead to other mechanical issues, including those with the transmission.

1. Compatibility of Tire and Rim Sizes

Different tire sizes can fit the same rim, provided the center diameter matches. A common modification is increasing rim size. When doing so, it's essential to adjust the tire size accordingly; larger rims typically require thinner tires to ensure they fit within the vehicle's wheel well. It is generally recommended that new tires have a diameter within 3% of the factory-recommended tires to maintain performance and safety.

2. Reasons for Changing Tires

Apart from aesthetic upgrades, tires are often replaced due to blowouts or general wear and tear. Ideally, all tires should be changed simultaneously. If that's not feasible, at least replace the front or rear tires together, depending on which tire needs replacing. If only one or a few tires are changed, it's crucial to use the same type and brand to avoid issues like loss of control, inaccurate speedometer readings, or damage to the vehicle's stability system.

3. Impact on Speedometer and Odometer

Changing tire sizes affects the accuracy of the speedometer and odometer, which are calibrated based on the original tire specifications. Larger tires increase the overall circumference, leading to lower speedometer and odometer readings than the actual speed and distance traveled. Conversely, smaller tires may result in higher readings. This discrepancy can lead to potential legal issues and affect driving safety.

While it's possible to safely change tire and wheel sizes, doing so requires careful consideration of compatibility, performance implications, and how it affects vehicle systems. It is always good to consult a professional.