Update: June 20, 2026: The US Tire Manufacturers Association has issued a written comment. You can find it here:  U.S. Tire Manufacturers Association Comments – Comments of the US Tire Manufacturers Association (USTMA) See the end of the article for details of the USTMA suggested changes. Pre-hearing: On June 10, 2026, the California Energy Commission […]

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. […]

On April 24, 2026, the California Energy Commission (CEC) released their proposed regulations concerning the rolling resistance of tires sold in California. This is a followup on a proposal made in February, 2023. Here’s a link to the actual proposal:  Californias Proposed Replacement Tire Efficiency Program Here’s a summary (details further down): Details: What/Who is […]

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 […]

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 […]

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 […]

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 […]

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. […]

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 […]

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 […]

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 […]

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 […]

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. […]

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 […]

Useful Lists and Such: 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 the YouTube videos. This guy is excellent!! Wheel-Size.com – A listing of the tire and wheel specifications of many […]

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

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 […]

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. […]

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 – […]