I know that non-vulcanized rubber is white and vulcanized is black. Also, the Ford Model T cars I've seen show white tires, yet big truck and bus models are depicted with black tires. Can anyone explain what was going on?

If I remember correctly (?) it is not the vulcanizing that makes the rubber black, but rather the addition of black pigments.
I do know that WW I aircraft tyres were typically light to medium shades of grey, and sometimes even pinkish.

So why are pigments added? Because the customer wants it?

(I am reminded when I worked at Sears, how we are told in school how manufacturers will omit parts to save money, but in reality, they do add parts which are useless, expensive, and dangerous because the customer wants them.)

Carbon black is an additive which increases the durability of rubber tires.

Here's Why Tires Are Black

Carbon Black was added to vulcanized latex rubber to increase is strength, especially in vehicle tires.

Thanks for the fascinating article!

When did they start adding carbon black? should a World War I armoured car have black or grey tyres? Anyone know?

World War I aircraft tires were not black, so the same might be reasonable for armoured cars. And armoured car tires look fairly light in black & white photos . . . . but much of that could be dust & dirt.

The answer is in the 4th paragraph of the article that Joe linked to (above).

Early automobile with tires that are not black

Note: vulcanizing is the manufacturing process of joining all the different materials, sidewalls and thickness of rubber in a tire. Tread, sidewalls, inner liners etc all have a different makeup, materials (steel belts, nylon weave stiffeners etc) and design and vulcanizing really referred to the heat process of bonding those together. By grandfather worked for Goodyear and Firestone way back in the day in the tire plants in Akron, Ohio. For awhile they used to dunk the tires in lye to remove residue, I remember seeing his hands after a week on the line and his hands would be dried and cracked from all that lye and chemical residues. Even bicycle tires use a similar process to lay in the bead that makes them retain their shape and seals them against a rim.

"Vulcanization (British: Vulcanisation) refers to a range of processes for hardening rubbers.[1] The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice; however, it has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides.

Vulcanization can therefore be defined as the curing of elastomers; with the terms 'vulcanization' and 'curing' sometimes used interchangeably in this context. It works by forming cross-links between sections of polymer chain which results in increased rigidity and durability, as well as other changes in the mechanical and electrical properties of the material.[2] Vulcanization, in common with the curing of other thermosetting polymers, is generally irreversible.

The word vulcanization is derived from Vulcan, the Roman god of fire and forge"

https://en.wikipedia.org/wiki/Vulcanization

Here's a vid on how they make tires today:
https://m.youtube.com/watch?v=1o9mVZxoayA

Not all tires are equal, most people don't even think about them. They usually buy from a dealer that knows what they need for their vehicle. Other people have specific requirements. I run a performance tire that has a speed rating in excess of 140mph, has excellent dry and wet performance and can handle the weight of a pickup truck. So I buy a 295/45/18V tire. The first number is the width in millimeters, 295mm is almost 12 inches. The second number is the width of the sidewall in percentage of the tire width so my sidewall is 295 x .45 or 132mm or 5.1 inches. The lower that number the narrower the sidewall and the higher the wider. The third number is the diameter of the rim. My rims are 18 inches in diameter. The V is a speed rating telling what is the max speed that tire is rated for. V rating is 149 mph.

Sadly to replace a tire costs me about $400 PER tire. Because of their composition they have a shorter tread life of about 25-30000 miles. Which for me is about 36 months of driving. For winter driving I have a set of studded truck tires I'll put on when the winter gets here.

And yes, I have pushed that speed rating a few times.

And here I thought it was invented by Mr Spock! (Too good of an open goal not to take the shot...)

@Patrick, what kind of truck are you driving that needs 140mph tires? Around here I'd soon become a pedestrian for cruising that fast...

And vulcanization was invented by Charles Goodyear right here in my hometown of Naugatuck, Connecticut, USA!
The U.S. Rubber Company was the lifeblood of the town until it closed in the 1980's.

I drive one of these: A Gen 2 Lightning

https://www.youtube.com/watch?v=87h4O_5lZcI

same color as mine, sounds like mine and I've had it 17 years last month. It had 12 miles on the clock when I drove off the lot.

Each Lightning has a build number. They built just over 4200 each year and every year they sold out. My build number #3488 of 4270 built in 03. Sonic Blue. I have a book I got when I purchased the truck that shows the breakdown of colors used that year.

It says the pigment was added around 1917. But we don't know when it became commonplace for various uses ie.... commercial vehicles, military applications, etc. Also.... when did those tires used by the military find their way to the various battlefields?
Seems like a tough thing to pin down.

WW I armoured cars appeared in different theatres and at different times. If black tires materialised in 1917 it is unlikely that they showed up on any front before the latter part of the year at the earliest, if at all. And maybe not even in 1918.
Armoured cars were pretty rare on the Western Front in 1917 and most of 1918.
What front are you considering? Remember, armoured cars were most common on the Eastern Front and in the Middle East.

Read this article from "India Rubber World", June 1920. In particular, the right hand column of page 581, paragraphs "Uses of Carbon Black" and "Rubber Tires". Note that they distinguish between lamp black and carbon black in the article, and the 1914 date applies only to carbon black, not lampblack. Lampblack may have been in heavy use well before that time.

It appears from photos that only pneumatic tires were light colors on WW I vehicles, and not even all of them. Solid rubber tires look black.

KL

I was thinking of the pictures on the ICM kit boxes. White tires on the older cars, black on the newer ones, black however on the trucks and busses, which presumably needed stronger rubber on the wheels to begin with. Yes, the civilian as well as the military. I have a FWD truck coming up in the future.

See Kurt’s comment above. The WWI FWD had solid rubber tires on spoked wheels, not pneumatic tires, therefore most likely very dark gray or black.
VR, Russ