You might have read reports that BF Goodrich tires run sizes smaller than they advertise. Is this true? Tire size can be a bit confusing, considering that tires have a ratio, height, and width. There are more numbers and figures going into your tire than just the size.
Are BFG tires true to size or do they run small?
BF Goodrich tires do tend to run smaller than they state. This is actually not at all uncommon amongst tire manufacturers. The reason for this mismeasurement is because tires are measured before they are mounted – not after. The difference is significant but doesn’t matter a lot.
Is the tire size deceptive advertising? Does it have an impact on your vehicle? We’ll dive into why tire manufacturers might have not quite the correct tire sizes listed and why enthusiasts need to know.
We’ve been in the automotive business for a while. We will sort through the research about which manufacturers do this – though the answer is all of them!
Why would a tire like BFG run small?
When a technician – or you, takes a shiny new pair of tires with new thread and gets ready to put them on a car – they probably won’t bother to measure them. The reality is that if you or the tech did measure your tires before putting them on the vehicle, they would probably be rather close.
Does a tire size change after mounting?
Once your vehicle’s tires are bearing the weight of often 1 to 3 tons of metal, the tires get a little compressed and can “loose” size. This means that if you were to measure your tires before putting them on your SUV, they would likely be a bit smaller after you actually mount them. A 32” tire might actually measure 31.25” after being put under the load of the vehicle.
Are tire sizes measured premounting?
Yes, they most often are. The reason for this is that the tire manufacturer has a good idea of how much your vehicle weighs, but they would need to provide a range of advertised sizes for a single tire.
Having a range of tire sizes within the same tire, based on the weight, would be confusing for service departments, tire manufacturers, and especially for customers.
Does a smaller tire impact anything?
Visually, if you notice that a tire makes your truck an inch shorter than you expected, then you might have a problem with the manufacturer. To be fair, most people won’t notice a one-inch difference in truck or SUV height, unless the difference creates a problem getting in and out – which it likely won’t.
The biggest area we could see an impact is in off-roading – although not by much. A half to three-quarters of an inch less clearance beneath a vehicle means a slightly higher risk of having the undercarriage bang into something.
Worried about tires being different sizes? You don’t need to. Most tires are made at consistent sizes across the same models. So if you just picked up a new set of BFGs, there’s a solid chance their quality control came through and the tires are within a small very measurement of one another.
How can I be sure my tires are the same size?
If you are worried, just be sure that your tires are all inflated properly. This means that all the tires should be within a pound or two of pressure of each other. The PSI measurement matters because additional air can make a tire just a bit taller or shorter, and you might notice the difference in ride quality.
How are tires measured?
Manufacturers start their measurement from the center of the tire from one side to the other, or vertically. Since tires are round, the measurement should be the same in both directions.
Tires are also measured at max compression, so if your tires are intentionally or unintentionally underinflated, you might see a height difference.
Is BFG unusually far off?
Nope. All tire manufacturers offer the same sizing method. You might discover a BFG that is ¾” smaller than measured when it is mounted – but know that another tire probably has the same compression.
Do a little research
If you are especially worried about a tire being mounted in a size smaller than you expected, we recommend looking up that specific tire and vehicle to see if the sizing changes when mounted. While you are unlikely to experience any actual difference in performance, buying a right-sized tire for something like off-roading could lead to problems, especially if the tire is off by an entire inch.
If you plan to buy tires from a tire shop or dealer, you could also ask them their experience – and to measure the tires before putting them on to see the difference. Measuring at the moment of install is easier at a dealer because you aren’t the one doing the work.
Smaller could be better
In some cases, a smaller than expected tire could be better. This is especially true if the tires you bought are potentially a bit big for your vehicle and risk rubbing the inside of the wheel well, sidewall, or suspension, especially on rough terrains.
How much is too small?
A tire shouldn’t be more than an inch to an inch and a half smaller than the advertised size. You should also check your vehicle weight, tire pressure, and any other factor that might compress the tire before acknowledging that a tire is too small.
Measuring tread width
You might also notice that some tires aren’t quite as wide as they claim to be – meaning that the treads themselves are slightly smaller than advertised. Much of the reason for this is a lack of standards for actually measuring tire width. Do you measure to the absolute edge? How about mud tires with chunky rubber exteriors? Part of the challenge is coming up with one way of measuring when different tire types are available.
When searching for tires, you might also notice that some tires don’t have a tread width measurement present. Sites like TireRack wouldn’t steer you wrong, so there isn’t much to worry about in regards to the slightly smaller or larger tread width.
Can you return tires if they are too small?
Many tire shops will refund or exchange if a tire is unexpected or different – so this isn’t exactly limited to believing tires are too small compared to their claimed measurement. If your BFGs are too small, consider Goodyear.