| How-To - Wheels and Tires
We've explained dozens of times over the years the difference between P-metric and imperial tire sizes so we won't cover a whole lot of the same ground, but we really haven't published a conversion chart that shows what the most commonly available sizes of P-metric 4x4 and off-road tires equate to in the commonly understood imperial measurements like 33x12.50R15 or 35x12.50R17.
In a nutshell, P-metric sizing is not quite as cut and dry as imperial, but on the same note, it's actually more informative. Where imperial measurements only give you information on the tire's advertised height, width, and wheel size, P-metric measurements tell you the width of the tire in millimeters, the percentage of that measurement the sidewall comprises related to the tire's aspect ratio, and the wheels size.
So, for P-metric you can get a quicker at-a-glance indication of how tall the tire's sidewalls might be. But then again, you can do a little quick math in your head and get an equally approximate idea of how tall an imperial tire's sidewall might be.
For example, in a 31x10.50R15 tire, the advertised height is 31 inches. Chances are it won't actually measure that tall in the real world, but we'll go with the advertised measurement for the sake of argument. The 10.50 inches is the tire's advertised width, usually taken at the tread, not the sidewall bulge. And the 15 is the size of the wheel it's designed for. So, in this case you've got a 31-inch tall tire for a 15-inch wheel. You know the wheel radius is 7.5-inches, and the tire radius is 15.5 inches. So, 7.5 minus 15.5 gets you approximately an 8-inch-tall sidewall.
For the P-metric equivalent, let's take a P265/75R15. In this case, the 265 is the tire's width at the tread and 75 is the ratio of the tire's sidewall height to the width, or in other words, the aspect ratio.
The way you find the aspect ratio value is simply the width is 75 percent of the tire's sidewall height, so in this case 75 percent of 265 is approximately 199mm. The smaller the aspect ratio number, the shorter the tire's sidewall height. Generally speaking, modern tires for larger wheel sizes will frequently have shorter sidewalls as the overall tire diameter increases. So let's take a look at how some of these P-metric numbers equate to the old imperial tire designations with which we're all familiar.
Metric Imperial
215/75R15 22.7x8.5
225/70R15 27.4x8.9
225/75R15 28.3x8.9
235/75R15 29.0x9.3
245/75R15 29.5x9.6
255/75R15 30.0x10.0
265/75R15 30.6x10.4
P-Metric to Imperial 16-inch WheelsMetric Imperial
205/85R16 29.
7x8.1
215/75R16 28.7x8.5
225/70R16 28.4x8.9
225/75R16 29.2x8.9
235/70R16 29.0x9.3
235/85R16 31.7x9.3
245/70R16 29.5x9.6
245/75R16 30.5x9.6
255/70R16 30.0x10.0
265/70R16 30.6x10.4
265/75R16 31.6x10.4
275/70R16 31.2x10.8
285/75R16 32.8x11.2
295/75R16 33.4x11.6
305/70R16 33.0x12.2
315/75R16 34.8x12.9
375/55R16 32.8x15.5
395/70R16 37.9x16.0
P-Metric to Imperial 17-inch WheelsMetric Imperial
215/65R17 28.0x8.5
225/60R17 27.6x8.9
225/65R17 28.5x8.
9
235/65R17 29.0x9.3
235/80R17 31.8x9.3
245/65R17 29.5x9.6
245/70R17 30.6x9.8
245/75R17 31.5x9.6
255/70R17 31.1x10.0
255/80R17 33.1x10.0
265/65R17 30.6x10.4
265/70R17 31.6x10.7
285/70R17 33.0x11.5
285/75R17 33.8x11.2
305/70R17 33.8x12.0
315/70R17 34.9x12.9
P-Metric to Imperial 18-inch WheelsMetric Imperial
225/55R18 27.7x8.9
225/60R18 28.6x8.9
235/60R18 29.1x9.3
235/65R18 30.0x9.3
245/60R18 29.6x9.6
255/55R18 29.0x10.0
255/70R18 32.1x10.0
265/60R18 30.
5x10.4
265/65R18 31.6x10.4
265/70R18 32.6x10.4
275/65R18 32.1x11.0
275/70R18 33.2x10.8
285/60R18 31.5x11.2
285/65R18 32.6x11.2
285/75R18 34.8x11.2
295/70R18 34.3x11.6
305/65R18 33.6x12.0
305/70R18 35.0x12.2
325/50R18 30.8x12.8
325/60R18 33.2x13.3
325/65R18 34.8x13.5
375/50R18 33.0x15.4
375/60R18 35.7x15.5
395/65R18 37.8x15.7
P-Metric to Imperial 20-inch WheelsMetric Imperial
245/50R20 29.6x9.6
245/60R20 31.6x9.6
255/50R20 30.0x10.0
255/55R20 31.
0x10.0
265/50R20 31.5x10.4
265/60R20 32.5x10.4
275/55R20 31.9x10.8
275/60R20 33.0x10.8
275/65R20 34.1x10.8
285/55R20 32.2x11.2
285/60R20 33.5x11.2
295/55R20 32.8x11.6
295/60R20 33.9x11.6
295/65R20 35.1x11.6
305/50R20 32.0x12.0
325/50R20 33.0x13.2
325/60R20 35.4x12.8
I got into my first four-wheel drive truck in the nineties after my father died.
He owned a 1987 Nissan Patrol pickup and I had always wanted to own a four-wheel drive vehicle. I had been a huge collector of off-road magazines over the years, but actually owning a four-wheel drive truck was still a huge learning experience for me.
One of the areas that was trial and error for me was the selection of tires based on size. The following is what I learned during the next few years about purchasing tires for an off-road truck.
Before reading on, make sure you're covered with an affordable car insurance policy.
When I got the vehicle, it came shod with 225 75 16s on split rims. These weren’t the stock tires on this vehicle, so I changed to the stock 7.50 16s soon after I started driving it. At 32.5 inches in height, these tires were quite a bit taller than the tires that came on the vehicle. The 225 75 16s were 29 inches tall.
The 225 75 16s that came on my truck are measured using an ISO Metric tire code. To calculate the height of the tire, you multiply the first number by the second, which is in hundredths (the aspect ratio).
Multiply that by two and then divide by 25.4, e.g, (225x.75x2)/25.4. Then add that to the last number, which is the rim height.
The height based on this formula is approximately 29 inches. The 7.50 16s that I purchased later are measured using a Light Truck numeric. The first three or four digits are the width of the tire in inches. The aspect ratio of these tires is one hundred percent. So using this formula, the height calculated would be about 31 inches.
However, most 7.50 16s are generally closer to 32 inches or a bit over. Flotation sizes such as 31 10.5 15 are more easily measured, as the height is the first two digits. Bear in mind, though, that the size on the side of the tire can vary slightly from manufacturer to manufacturer.
The static loaded radius of a tire is the height from the ground to the center of the wheel when maximally loaded. In comparing two tire sizes, the difference in the static loaded radiuses of both tires will be the amount of ground clearance gained or lost between both tires.
The radius is a bit less than the actual diameter of the tire, depending on the weight of the vehicle. The increase in height/ground clearance on my truck was 1.5 inches. The height increase was quite visibly noticeable.
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Another noticeable effect of putting on taller tires was the decrease in RPM. With the shorter tires, the vehicle was quite revvy even in fifth gear. With the taller tires, the Patrol became much quieter. This is because taller tires decrease the gear ratio of your car. The stock gear ratio on my vehicle was 4.88. Moving from a 29-inch to a 32-inch tire decreased that gear ratio by 10%.
Bearing in mind that the 7.50s were stock, the effective gear ratio on the 225s was 110% more, or 5.36 (a lower gear). No wonder the engine was so revvy! There are many sites online where you can calculate the effect on gearing that a change in tire size will have on RPM for your vehicle.
Effects that a change to a taller tire will have include:
Nissan Patrols, like Toyota Landcruisers, can fit up to a 33-inch tire (depending on width) without a lift. Most older mid-sized to full-sized SUVs are only able to fit up to a 31-inch tire. Some of today's SUVs can fit up to a 32 or even a 33 in some cases without a lift.If you want to maintain the performance of your truck after changing to larger tires, then a swap to lower gearing in your differential will go a long way toward keeping the RPM in the same range, providing you lower the gear ratio the same percentage that you increase the height of the tire. That may not be necessary if the increase is small and you can put up with a slight loss of power.
Larger tires will definitely give you an advantage in driving off-road, especially over more extreme terrain. An inch or so over stock height should be well within budget, so long as one considers the aforementioned points in buying off-road tires.
Just make sure you're covered with an affordable car insurance policy.
The labeling of tires manufactured in America is very different from European designations. Therefore, drivers constantly have to convert inches to millimeters or centimeters. Only by making such calculations, you can choose the right wheel for your car. nine0003
Contents
The Russian SUV comes with wheels that are slightly smaller in diameter than conventional SUVs. The standard size of foreign cars is 29 inches or 235/75R15.
Domestic SUV (Niva) is equipped with 175/80R15 wheels at the factory. On such tires, the car quickly burrows into the mud, hardly moves along our impassability. nine0003
To correct this situation, you need to install 29 inch tires. It will increase the clearance by 25 mm. If you install tires 31 inches, the ground clearance will increase by 50 mm. To install such wheels, you only need to change the wheel arches.
It will be necessary to increase their dimensions.
Most Jeeps use tires marked 31x10.5R15.
31 here refers to the inch diameter of the wheel. One inch, as you know, corresponds to two and a half centimeters, and to be completely accurate, then 2.54 cm. In other words, after the transfer, D will become equal to 78.7 cm.
This marking is quite in demand, because it is convenient, as it shows the size of the wheel with the disk parameters already taken into account.
The wheel diameter 31x10.5R15 is almost equal in dimensions to the tire with the designation 31x10.5R16. The only difference will be a reduction in tire profile by 2.5 cm.
10.5 - tire width in inches. But this value is not entirely accurate, since when converted from inches to traditional centimeters, it will turn out to be 26.5 cm.
However, when measuring this value with a regular ruler, the value will fluctuate within 23 cm. it will be possible to talk about a width of 26.
5 cm.
You should always remember this nuance if you decide to install the maximum tire size in the arch of an SUV.
This measurement system is much more difficult to use. Take rubber marked 265-75-15.
265 mm - tire width. Just like in the inch system, its actual width will be approximately 230-235 mm.
75 - profile height in millimeters. To get the true value, you need to take 75% of 265 mm. It will be 198.75 mm. This number is then multiplied by two. This is because the total wheel diameter is D of the rim plus twice the profile height.
In our case, it is 15 inches. As a result, after the calculations, we get a D disk of 381 mm. Total wheel D: 397.5 + 381 = 778 mm or 77.8 centimeters.
R15 - radial rubber. Disc diameter is in inches. Always a surprise. Why is the inch designation left in the metric system.
If you look closely at these two systems, you will notice a slight difference, about 1.1 centimeters. It does not affect the design and installation of the wheels in any way.
nine0003
Today, a large number of various calculators are offered on the Internet for the correct calculation of tire size. All of them work completely free of charge and make it much easier to find the right tire size.
You can get acquainted with the rating of summer tires 2019 on our website
We have compiled a table of the most common sizes, perhaps it will help you quickly find the right wheel size.
| Key | Дюймы |
| 235/65R16 | 28,0 |
| 235/75R15 | 28,9 |
| 225/75R16 | 29,3 |
| 245/70R16 | 29.5 |
| 285/60R16 | 29.5 |
| 225/85R15 | |
| 245/75r16 | 30518 |
| 265/70R16 | 30,6 |
| 305/60R17 | 31,4 |
| 265/70R17 | 31,6 |
| 265/75R16 | 31,6 |
| 235 /85R16 | 31,7 |
| 285/70R16 | 31,7 |
| 285/70R17 | 32,7 |
| 285/75R16 | 32,8 |
| 305/70R16 | 32.8 |
| 255/85R16 | 33.1 |
| 305/75R16 | 34.0 |
You can familiarize yourself with the 2019 summer tire rating
ADBLOCK
DETECTOR
Matching tires and rims is an important step towards safety and driving comfort for any driver. A frivolous attitude to this issue is fraught with serious consequences, both for the technical condition of the vehicle, and for the health and life of drivers and passengers.
Consider this problem on SUVs, crossovers or pickup trucks of various classes. Of course, here the size range is not so large, which makes it easier to select discs for tires. To begin with, it is worth recalling what indicators are important when deciding whether tires and wheels match:
Wheel marking with dimensions R13 4x98 ET35 J5 D58.6
The table below shows almost all off-road vehicle wheel sizes. We remind you that on our website there is also an option for selecting wheels by car brand . Also on our website there is similar information regarding passenger cars .
Tire and wheel matching table
| Wheel diameter | Tire size | Wheel rim width (inches) | ||
| Minimum | Recommended | Maximum | ||
| 16" | 7. 50R16 | 5.50 | 6.00 | 6.50 |
| 235/85R16 | 6.0 | 6.5 | 7.5 | |
| 15" | 195/80R15 | 5.0 | 5.5 | 6.5 |
| 215/80R15 | 5.5 | 6.0 | 7.0 | |
| 16" | 205/80R16 | 5.0 | 5.5 | 7.0 |
| 215/80R16 | 5.5 | 6.0 | 7.0 | |
| 15" | 215/75R15 | 5.5 | 6. 0 | 7.0 |
| 225/75R15 | 6.0 | 6.0 | 7.5 | |
| 235/75R15 | 6.0 | 6.5 | 8.0 | |
| 255/75R15 | 6.5 | 7.0 | 8.5 | |
| 16" | 225/75R16 | 6.0 | 6.0 | 7.5 |
| 15" | 195/70R15 | 5.0 | 6.0 | 6.5 |
| 205/70R15 | 5.0 | 6.0 | 7.0 | |
| 265/70R15 | 7. 0 | 8.0 | 9.0 | |
| 16" | 215/70R16 | 5.5 | 6.5 | 7.0 |
| 225/70R16 | 6.0 | 6.5 | 7.5 | |
| 235/70R16 | nine0075 6.07.0 | 8.0 | ||
| 245/70R16 | 6.5 | 7.0 | 8.0 | |
| 265/70R16 | 7.0 | 8.0 | 9.0 | |
| 275/70R16 | 7.0 | 8.0 | 9.0 | |
| 17" | 225/70R17 | 6. 0 | 6.5 | 7.5 |
| 265/70R17 | 7.0 | 8.0 | 9.0 | |
| 15" | 185/65R15 | 5.0 | 5.5 | 6.5 |
| 16" | 215/65R16 | 6.0 | nine0075 6.57.5 | |
| 255/65R16 | 7.0 | 7.5 | 9.0 | |
| 17" | 235/65R17 | 6.5 | 7.0 | 8.5 |
| 245/65R17 | 7.0 | 7.0 | 8.5 | |
| 265/65R17 | 7. 5 | 8.0 | 9.5 | |
| 275/65R17 | 7.5 | 8.0 | 9.5 | |
| 16" | 215/60R16 | 6.0 | 6.5 | 7.5 |
| 236/60R16 | 6.5 | 7.0 | 8.5 | |
| 18" | 235/60R18 | 6.5 | 7.0 | 8.5 |
| 275/60R18 | 7.5 | 8.0 | 9.5 | |
| 285/60R18 | 8.0 | 8.5 | 10.0 | |
| 17" | 225/55R17 | nine0075 6.7.0 | 8.0 | |
| 235/55R17 | 6.5 | 7.5 | 8.5 | |
| 275/55R17 | 7.5 | 8.5 | 9.5 | |
| 18" | 255/55R18 | 7.0 | 8.0 | 9.0 |
| 19" | 255/55R19 | 7.0 | 8.0 | 9.0 |
| 275/55R19 | 7.5 | 8.5 | 9.5 | |
| 285/55R19 | 8.0 | 9.0 | 10.0 | |
| 17" | 255/50R17 | 7. 0 | nine0075 8.0 9.0 | |
| 18" | 235/50R18 | 6.5 | 7.5 | 8.5 |
| 285/50R18 | 8.0 | 9.0 | 10.0 | |
| 19" | 255/50R19 | 7.0 | 8.0 | 9.0 |
| 20" | 255/50R20 | 7.0 | 8.0 | 9.0 |
| 275/50R20 | 7.5 | 8.5 | 9.5 | |
| 18" | 255/45R18 | 8.0 | 8.5 | 9. 5 |
| 19" | 235/45R19 | 7.5 | 8.0 | 9.0 |
| 275/45R19 | 8.5 | 9.0 | 10.5 | |
| 285/45R19 | 9.0 | 9.5 | 10.5 | |
| 20" | 265/45R20 | 8.5 | 9.0 | 10.0 |
| 19" | 255/40R19 | 8.5 | 9.0 | 10.0 |
| 20" | 275/40R20 | 9.0 | 9.5 | 11.0 |
| 20" | 315/35R20 | 10. 5 | 11.0 | 12.5 | nine0083
| 21" | 285/35R21 | 9.5 | 10.0 | 11.0 |
| 22" | 285/35R22 | 9.5 | 10.0 | 11.0 |
| 21" | 325/30R21 | 11.5 | 11.5 | 13.0 |
| 22" | 295/30R22 | 10.5 | 10.5 | 11.5 |
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