Dalton’s Law says that the total pressure of a gas mixture is the sum of the partial pressures of the individual gases. John Dalton observed this in 1801. That’s John Dalton to the right (below). The law is one of several involving gases – and since air is a mixture of gases ………. Air is […]

For the month of September, 2026: Just when I thought there was nothing new for September, Tire Business, an industry newspaper, published an article about the new California tire regulations with lots of soundbites from various people within the industry. One of those was from Roy Littlefield of the TIA (Tire Industry Association), a tire […]

Force and Moment Tire engineers use the term “Force and Moment” to describe how tires generate cornering forces. But it’s not just forces being generated, there are also torques (moments) generated. So, upfront, I will confess that this area of tires is a weak spot for me. The good news is that I don’t have […]

Once again, I am starting off the blog with an entry on the California Energy Commission and their proposed tire regulations. This time it’s the fact that on Friday August 7, 2026, they announced that this item was on the agenda for the CEC business meeting on Monday Aug 17, 2026, 10:00am Pactific Time. The […]

Euro 7 is the seventh set of regulations involving vehicle emissions – and this time, they’ve included tires as part of the regulation. What effect does Euro7 have on tires? For the first time, tires are part of the European emission standards – in particular, the particles generated when tires wear. Here’s the timeline: In […]

Link to EPREL – The EU’s website that lists EVERYTHING rated with an energy label – including washing machines, air conditioners, ovens ……… and tires! EPREL Public website Here’s a link to the regulation: eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32020R0740 And a link to a related document: L_2009200EN.01000101.xml Please note that below is a discussion on the latest label- revised […]

In the process of researching the European Union’s tire label, I stumbled on the fact that the label covers more than passenger car tires. It also includes what they call “Van tires” and “Truck tires” – they label those C2, and C3, with C1 = passenger car tires. Van tires (C2) is the equivalent of […]

Update: Aug 1, 2026: On July 17, 2026, the California Energy Commission issued some changes to their proposed tire regulations. I’ve updated this webpage to show those changes – with a strikethrough (strikethrough) for the old verbiage and bolded italics (bolded italics) for new verbiage! Here’s a link to the Docket. The one of interest […]

Below is a copy of the letter I sent to the California Energy Commission commenting on their proposed regulation. Here’s a link to my webpage on the regulations: California Energy Commission: California’s Proposed Replacement Tire Efficiency Program – April, 2026 – Barry’s Tire Tech

Blog – July 1, 2026 In April, 2026, the California Energy Commission (CEC) announced their latest version of their proposed tire regulations.  I cover that in a separate post – here!: California Energy Commission: California’s Proposed Replacement Tire Efficiency Program – April, 2026 – Barry’s Tire Tech.  In this blog entry, I’m going to cover […]

Please note: Tire Business is a bi-monthly publication of news of interest to those of us in the tire industry. Among the things they publish are summaries of various things – like who has plants, where. In this case, it’s brands and who owns them. Be aware: Enjoy! Page 10: Page 12: Page 14: Page […]

Update July 15, 2026: The CEC issued a transcript of the comments: https://links-2.govdelivery.com/CL0/https:%2F%2Fefiling.energy.ca.gov%2FGetDocument.aspx%3FDocumentContentId=108977%26tn=271437%26utm_medium=email%26utm_source=govdelivery/1/0101019f62d20f98-10aed5ab-ad27-47b4-9690-f2c4587c66e1-000000/bbpI5CyhhHFnK8i8zqdVsZE5mRZuyo_hUVLH8TsjgPI=452 There were several comments that are interesting. John Baldwin of Discount Tire said that if the Phase 2 limits were implemented today, 70% of the tires currently on the market would be banned. (Page 66). Jay Spears of Continental Tire said there […]

Things of interest in the world of tires for the month of May, 2026. ********************* On May 13, 2026, the California Energy Commission announced a public hearing of their new proposed regulations for June 10, 2026. I don’t expect much out of this hearing other than a lot of complaints. ****************************** Yeah, not a lot […]

This is a controversial subject! So I am going to try to lay out the case as best I can – and as neutrally as I can. Setting the Stage! Here’s the recommendation as it appears in the USTMA (US Tire Manufacturers Association) publication “Care and Service of Passenger and Light Truck Tires”. “When replacing […]

I stumbled on a YouTube video where a guy was applying – his words – “14 ply tires” to his travel trailer. For those who are not familiar, travel trailers usually come with ST tires. ST tires are uniquely an American sizing system. ST meaning Special Trailer – special, as in not for semi-tractor trailers. […]

Jalopnik had an article talking about Michelin putting RFID (Radio Frequency Identification) chips in passenger car tires and how they weren’t active, but passive – that is they could not transmit, only respond, because they didn’t have batteries. What that meant was that the chips could only tell a reader what they were, not where […]

I’ve seen this question enough to warrant a webpage. Here goes!! Please Note: 7.00-15: Important Statistics A 7.00-15 is 29.6″ in diameter, with a width of 8.0″ on a 5.50″ wide wheel with an allowable rim width range of 5″ to 6.5″. The load carrying capacity is 2040# single at 65 psi for a Load […]

I’ve been struggling to understand how water vapor affects tire pressure. So I launched an effort to do so. There were a number of questions: When is water a gas and when is it a liquid? Let’s start with the most important bit of information needed: How do we determine when water is a gas […]

Another NASCAR incident: At the Pheonix race, there were a lot of tire …… ah …… disablements. Road hazards are a thing and since there were some brake parts failing, it’s inevitable. But there were quite a few tire issues, and given that it was pretty warm, some of them had to be tire structural […]

This is a bit of a departure from my usual stuff. It’s an article about a particular problem that was encountered and how someone dealt with it. If this proves popular, I’ll do more. First, if you have safety problems with a vehicle or related products, and you think it’s a problem the manufacturer isn’t […]

Yes, I didn’t have a monthly blog for January. Apparently stuff doesn’t happen in January! But February is different….. and at the first NSACAR race of the year – the Clash at Bowman-Gray in Winston-Salem, North Carolina – it was CCCCCooooold!! – and rainy and sleety! During one of the lulls in the action, Fox […]

For practical purposes, when people talk about inflation pressure, they mean “cold” inflation pressure – that is: the tire and the air inside it are at the same temperature as the surrounding environment. If people want to talk about tire pressures while the vehicle is operating, they will use the words “warm”, or “hot”, or […]

The photo above is of a “greige roll” – a roll of tire cord, before it gets a coating of rubber by way of a machine called a calendar. The roll has tiny (and breakable) cross cords (called a weft) to hold the cords in proper position during the calendaring operation. Once calendared, the fabric […]

This time it’s tire sizes that aren’t covered by a tire standardizing organization. 445/50-15 & 515/45-15 I stumbled across 2 tire sizes I was unfamiliar with. The tires are 445/50-15 and 515/45-15 Pro-Trac Street Pro – apparently made by Coker Tire and sold by a few other outlets, like Summit Racing. The 445/50-15 is 17.8″ […]

Odd Ducks: This article is the first in a series about unusual things I find – things that don’t fit the narrative I have been preaching – In this case, it’s about interchanging tires of the same type regardless of where they are made. Take the case of C Metric 225/75R16. Background Info: There are […]

Wheels, Rims, and Spiders! OH MY!: It’s time I talked about those other things that make tires work – Rims. OK, before everyone has a conniption – The difference between a rim and a wheel is this: A rim is the hoop shaped part that a tire is mounted on. See an example to the […]

The Department of Transportation (DOT) is the US governmental agency that regulates all forms of transportation in the US. That includes air travel (FAA), rail travel, travel on water, and what we are interested in, roads (through the National Highway and Traffic Safety Administration – NHTSA – pronounced Nit-Sah). As part of that, NHTSA also […]

I’m going to divide this into 4 parts: To the right (below) is an image of a wallchart published by the US Tire Manufacturers Association (USTMA) covering the procedure to repair passenger and light truck tires. Do not bother to download this image, as it is not detailed enough to actually be read. Instead, buy […]

Match Mounting: Here’s what you should get from this webpage: What is Match Mounting? Nothing is perfectly round – and that includes both tires and wheels. But if you can match the high point of the tire to the low point of the wheel, the assembly will be “rounder”. For wheels, it is pretty simple. […]

Racing Tires: There are many kinds of racing. When someone invents a vehicle or a way for humans to compete against each other, they create a race around that! I’ve posted some photos of racing events that use tires. Usually we don’t think of those tires as “Racing Tires”. Yet, each of those has tires […]

I’m just posting these because they contain some good information. Summary: The source report and a later fact sheet are below.

I am on a NHTSA email list for recalls. Every time there is a new recall, I get a notice. I always read them to see if there is anything interesting. And in December I did get one that is interesting. 82,000 tires are being recalled in various sizes going all the way back to […]

This article is about Winter and All Weather tires. It includes information about the tests involved. Winter and All Weather Tires: Updated April, 2026: Added a note about Truck/Bus tires. Updated January, 2026: I added a line or 2 about studded tires below. Updated Apr, 2024 In the Apr 8, 2024 issue of Tire Business, […]

This is a special blog post to cover this issue. Here’s the news article Jury Awards $220 Million Against Michelin After Deadly Ford SUV Tire Blowout – Autoblog First let me say, I offer my sympathies to all the people involved in this. It’s a horrible situation, one I do not want to make worse. […]

RunFlat Tires First, nomenclature: I am going to discuss tires that don’t need internal air pressure to operate. To ensure I am clear, I am going to reference those tires using the term “RunFlat” (notice the lack of a space and the Caps!). I am going to use the term “run flat” to mean tires […]

December 1, 2025: Tire Business, a publication that reports on tire related stories, reports that the Safe Tread Alliance (STA), a coalition of industry leaders and safety advocates, is advocating replacing the “Penny Test” with the “Quarter Test” for tire replacement – that is a change to 4/32nds as the standard removal level. The Penny Test results […]

Tire failure on a schoolbus leads to the death of an eighth grade student. Revision: The link below is to a more up-to-date news article Page A1 | Post and Courier Columbia E-Paper /end revision The news reported that back in April, 2025, a schoolbus suffered a front tire failure, flipped and killed an 8th […]

Let’s assume for the moment that there is an extra glob (How’s that for a technical term!) of rubber on the edge of the tread of a tire – and that the tire is mounted on a rim and inflated. If this glob has significant weight, it could cause a vibration in the vehicle. Let’s […]

Barry talks about HL tires – tires that were designed with additional load carrying capacity compared to regular passenger car tires. The intention was to provide a way for car manufacturers to avoid tire packaging issues on EV’s. HL Tires This article is being written in July, 2022. The first HL tires just came on […]

OK, not “All New”. Just the look is new. Update April, 2026: It’s been 6 months since the website was relaunched, so maybe “NEW” just doesn’t seem to be the right word, but I’m unsure what the right words is. Oh, well!! A special thanks to Michael Staake of Wag Websites for designing this and […]

This is the first of a series utilizing this new format. This one is about how much can be revealed simply by reading recall documents. 19 October, 2025: Yesterday, I got a notice from NHTSA about a tire recall. The company is not important, but they were recalling several sizes of tires, all from the […]

Low Profile vs High Profile Tires: This article was prompted by a YouTube video on the same subject that was ……..ah …….. Let’s just say I thought I could do a better job. But let me start by saying, the variability within a given size is quite large – so large that tires on the extremes could be the reverse […]

Tire Warranties When browsing the internet, I frequently come across folks with a tire problem and wondering if the tire is covered under warranty. This article is an attempt to answer that question. Pro Tip Call the tire manufacturer if you have a warranty situation. Not only will they guide you to a tire dealer […]

TRX Tires By the late 1970’s, the transition from bias ply tires to radials was more or less complete. The typical aspect ratios were 80, 78, and 75, with 70 series considered low profile. It was known that the lower the aspect ratio, the better the handling, but the worse the ride. The TRX was […]

This article is going to compare bias ply tires with radials. While I will be referencing passenger car tires, the comparison would apply to any type of tire. There’s a summary at the bottom of the page, but read the introductory paragraphs first. They explain how I am organizing this. Everyone needs to be aware […]

Other Types of Tires: This website has been talking almost exclusively about passenger car tires. Occasionally, I will talk about Light Truck tires. In this article, I am going to address the other kinds of tires. Just for reference, I am going to follow the order tire standardizing organizations follow (and – YES! – they […]

This is the second in a series of articles about the rubber chemistry of tires. I am NOT a rubber chemist and my knowledge is rather limited, so I could use some help. If you are a rubber chemist, please contact me. Mills: One of the most fundamental pieces of machinery involved in rubber processing is a […]

This is the first of several articles about the chemistry of the rubber used in tires. Obligatory: I am not a rubber chemist and my knowledge is severely limited. I could use some help writing these articles, so if you are a rubber chemist, please contact me. This first article is about the kinds of […]

Key Takeaways Definitions When I use the term “EV”, I mean “BEV”—Battery Electric Vehicle—that is, vehicles which only have an electric motor for propulsion. Peculiarities of EVs There are a number of things peculiar about EVs: I’m going to take each of these individually. Range Where tires play a role here is in rolling resistance. […]

Retreads have an undeservedly bad reputation – partially because early retreads DID deserve it, but they no longer do – and partially because of a huge misunderstanding. Ya’ see, many folks think that if they see a failed truck tire along the interstate, that it’s a retread failure. But if you can see wire, then the carcass […]

Revised: December, 2024: At the bottom of this page, see the addition of Tyre Reviews Video (Jonathan Benson). /end Dec 2024 revision: I get a lot of questions about these kinds of tires. It’s pretty simple – REALLY! Directional Tires will have an arrow on the sidewall. If it doesn’t have an arrow, it’s non-directional! and it doesn’t […]

DOT Codes are also known as the Serial Number or the TIN (Tire Identification Number) I get a lot of questions about how old a tire is. You can tell that – and a lot of other things – by reading (and decoding) the DOT code. Update Dec, 2024: Tire Business, a newspaper of interest to tire dealers, published […]

What you should get from this page: You will hear various recommendations about tire aging: How many years, how bad are the cracks, from date of production or date of install, etc. This page will give you MY recommendations and the justification behind them. They may not be perfect, but at least you will know where they […]

In the article on weather cracking and tire aging – here!– I stated I couldn’t figure out why the tire return pattern didn’t change – it should have changed timing and shifted to a later return pattern, indicating the failures were occurring later in life. Instead, it only dropped in magnitude.I now have an explanation. […]

Want to know if your tires are overloaded? Below I present a test procedure to figure that out and a spreadsheet to help with the calculations. Enjoy! Test Procedure: Before starting out on an extended trip (at least an hour!), measure and record both the inflation pressures and the ambient temperature. It’s also a good […]

Uniform Tire Quality Grading (UTQG) is a US system for passenger car tires to allow consumers to make better choices when buying tires. This article is about the details. What you should get from this page: UTQG ratings were a long time in gestation. The tire manufacturers resisted the regulation quite strongly. Their principal argument […]

This article is about travel trailers (RV’s) that have ST type tires. Other kinds of trailers or other types of tires on RV trailers are not specifically addressed here. HOWEVER, if you have a trailer of any sort you may find the information of value Tips for ST tires: When I originally published this webpage, […]

In this page, I am going to talk about how tire brands work. I am not going to talk about quality or compare tire brands in any way. It’s really important to realize that for every statement I make below, there are exceptions—so many in fact, I may not remember to point them all out. […]

This article is about how you can’t calculate the size of a tire’s footprint. That is, the inflation pressure is not equal to the average foot pressure and you can’t calculate the size of the footprint even if you know the load and the inflation pressure. Included are a ton of examples gleaned from the […]

Vehicle Drift and Pulls and Tire Conicity: What you should get from this page: Tire Conicity: The root word is “cone”. It’s a tire property where the tire is exerting a sideways force when rolling. The force can be pointed inwards towards the vehicle (negative) or outwards, away from the vehicle (positive) – and of […]

What you should get from this page: To aid in this, I’ve created the chart below. Right click on the chart, Open image in new tab, and once the new tab is open, print it out and take it with you. Please note that it is possible that after this was written, the tolerances might […]

Rolling Resistance and Fuel Economy (Continued): Revised December 2025: I brought the page up to date and incorporated all the previous revisions. I don’t think I need to enumerate those any longer. /end Dec, 2025 revision If you don’t want to go through the entire page to get what is important: 1) There can be […]

Rolling Resistance and Fuel Economy: I once saw a study done by a vehicle manufacturer that said that tires consume 17% of the fuel consumption for a vehicle. Given the source, I assume that this is based on the EPA test used for determining the fuel consumption of a vehicle Further, this 17% means not […]

Work in Process If you came here to research what is causing your unusual and/or uneven tire wear, I suggest you start with this page on normal tire wear It will set the stage for what comes below. Unusual and Uneven Tire Wear: This page is mostly about identifying the cause of unusual tire wear – […]

If you came here to research what is causing your odd and/or uneven tire wear, I suggest you read this page first, then go here! Most tire wear occurs when cornering. Driving straight ahead is almost free. Put another way, there is a difference between “City Driving” and “Country Driving” and country driving results in […]

This article is about tire noise – what causes it, how tire manufacturers reduce it, and how the consumer can reduce it. Tire Noise and Noise Testing: I am going to talk about how tire manufacturers try to reduce the noise that tires generate. That may help you select a tire that doesn’t generate as […]

Tire Traction & Traction Testing – Wet: This article is about wet traction testing. It includes details of the UTQG rating test for (wet) traction. If you haven’t already, it would be better if you read my webpage on dry traction here. This page will make a lot more sense if you do. I address snow […]

This article is about dry traction testing. Read this one BEFORE reading the article on Wet Traction here. I address snow and ice traction testing here as part of the article on Winter and All Weather tires. The photo above is of a traction trailer and its tow vehicle. Below I will discuss how tires get tested […]

DO NOT MOUNT A 16″ TIRE ON A 16.5″ RIM! DO NOT USE MORE THAN 40 PSI WHEN SEATING A BEAD! Serious injury or death may result for failure to follow the above instructions. Here’s the full warning: RMA Warning about 16.5″ Tires I’ve started this web page with a warning. This is such a dangerous issue that it […]

Useful Lists and Such: EPREL Public website – EU’s listing of the rating for stuff with an energy label – including tires. Tyre Reviews.com – Jonathan Benson, a UK based journalist (now living in Salt Lake City), does tire testing and publishes them on YouTube. This link takes you to his website, which has links to […]

From Top Tire Review: Top Tire Review – Bringing tire knowledge to everyone, one tire at a time

Here’s where this table comes from: UTQG table – Top Tire Review

Speed Ratings: Before we start, I want to remind everyone that these web pages are generally about passenger car tires. When I discuss something that doesn’t apply to passenger car tires, hopefully it will be obvious. Here’s what you should get from this page: Historical background: Speed ratings are a 1960’s European invention in response […]

Original Equipment tires are tires that are supplied to the vehicle manufacturer’s assembly plant. These tires would be the ones on the vehicle when it comes off the end of the assembly line. This would include the spare – whether it is a minispare, donut, fullsized temporary, or regular tire. Throughout the rest of this […]

From time to time, I will get questions concerning the use of modern tires in place of the tires that came originally on a vintage vehicle. By vintage, I mean any vehicle that was produced before the advent of the current tire sizing system. If you don’t have a good grasp of how tire sizing […]

There are several tire standardizing organizations throughout the world, but I am going to concentrate on just three of them: The Tire and Rim Association (TRA) – The US organization (The cover of the 2005 Yearbook is at the top of this page) The European Tyre and Rim Technical Organization (ETRTO) – Europe (The cover […]

This article is about how tire dimensions work. – how they are specified by the tire standardizing organizations. If you haven’t read up on Tire Standardizing Organizations, I suggest you do so. It will help you understand this page better: Barry’s Tire Tech – Tire Standardizing Organizations Also, Tire Rack has done such a good […]

This article explains how tire load tables work. They define the relationship between inflation pressure and load carrying capacity. If you haven’t read up on Tire Standardizing Organizations, I suggest you do so. It will help you understand this page better: Barry’s Tire Tech – Tire Standardizing Organizations Below is a scan from the 2005 […]

WASHINGTON, DC, Aug. 9, 2000 — Saying the safety of consumers is the company’s first concern, today Bridgestone/Firestone, Inc., announced a voluntary recall of all Firestone Radial ATX and Radial ATX II tires in size P235/75R15 produced in North America, including Mexico, and Wilderness AT tires in size P235/75R15 produced at the Decatur, Illinois plant. […]

One of the fundamentals about tires is sizing. There is a lot of confusion concerning tire sizing and this is going to explain it in general terms and basically how it works. As a general rule, tire sizing describes the physical dimensions of a tire – but that is only part of the story. It […]

There aren’t any real advantages to using nitrogen in a street tire. Enough time has gone by, and enough research has been done, to be able to back up what effect using nitrogen has as an inflation medium. Rather than repeat the myths surrounding nitrogen as an inflation medium – thereby reinforcing the myth – […]

These are charts showing the various kinds and configurations of balance weights for wheels.

As published by Tire Business, December 16, 2024

1950-51 TRA Cover Page: 1950-51 TRA Page 1-01: 1950-51 TRA Page 1-02: 1950-51 TRA Page 1-03: 1950-51 TRA Page 1-04: 1950-51 TRA Page 1-05: 1950-51 TRA Page 1-06: 1950-51 TRA Page 2-01: 1950-51 TRA Page 2-02: 1950-51 TRA Page 2-03: 1950-51 TRA Page 2-04: 1950-51 TRA Page 2-05: 1950-51 TRA Page 2-06: 1950-51 TRA Page […]

1960 TRA Cover Page: 1960 TRA Page 1-01: 1960 TRA Page 1-02: 1960 TRA Page 1-03: 1960 TRA Page 1-04: 1960 TRA Page 1-05: 1960 TRA Page 1-06: 1960 TRA Page 1-07: 1960 TRA Page 2-01: 1960 TRA Page 2-02: 1960 TRA Page 2-03: 1960 TRA Page 2-04: 1960 TRA Page 2-05: 1960 TRA Page […]