UK: New fuel economy test could signal the death of the big wheel - Sensationalist Headlines

The trend for even mainstream cars to wear big 18-inch or 19-inch alloy wheels may soon be about to end – and it’s upcoming new WLTP fuel economy regulations that are behind it. The size of wheels and width of tyres have a significant impact on the CO2 emissions and fuel economy of cars. The current, outdated NEDC fuel economy test has long failed to expose this, which is why wheels have grown so much over the years. However, early evidence of the new WLTP test suggest it is much more clearly revealing the effects big wheels have on emissions and economy – and experts at Kwik Fit believe this could reverse the trend for ever-larger wheels. The effect will be particularly obvious to company car drivers, who pay tax based on the CO2 emissions of their car. Fleet sales director Andy Fern predicts “we may see vehicle manufacturers end the trend for larger wheels”. https://www.motoringresearch.com/car-news/wltp-test-signal-death-of-big-wheel/

Though they didn't outright say it, I'd hope they're not seriously thinking of discouraging wider wheels. Wider wheels offer a lot more grip and very important from a safety standpoint.

Well tax is based on CO2 emissions, which will increase as your mpg goes down (obviously). Wider tyres have higher rolling resistance, so yeah you would pay more for them unless you have a BEV.

That's not going to past muster. No one is going to formalise these regs if it impedes vehicle safety.

here's ur new wheel, fam https://d.ibtimes.co.uk/en/full/1450114/bmw-i3-tyres.jpg

eeeeeeeeeeeeeeeeeeewwwww

Sounds like the big wheels won't keep on turning in the UK

Always? In any conditions? Irrespective of suspension geometry? Your contact patch size is more or less fixed by tyre pressure and vehicle weight. Wider tyres do not mean you have more rubber on the road. The patch shape does vary, but the effects of this are complex. You also need to consider that tyre width is taken into account when designing suspension. For example, if you put fat tyres on that BMW i3 above, it could handle worse. Notice how factory tunes of street cars never go more than an inch or so wider than the stock wheels (without a suspension redesign), even though forum wisdom says you should go as wide as possible. Wider tyres are generally safer in snow (which is rare in the UK) Narrower tyres are generally safer in rain (which is every other day in the UK)

It's already been agreed within Europe. The WLTP procedure will be implemented by all UNECE members (EU-28, Norway, Iceland, Switzerland/Liechtenstein, Turkey and Israel) according to the above timeline. Other countries that signed the WLTP agreement, such as China, Japan, South Korea, Russia, India and the USA, are currently in a monitoring position and have not yet communicated any implementation timeline. The CO2 taxation thing is just how UK law is implemented, with tax based on CO2 emissions and the new testing procedures it impacts it because they are more accurate.

There are rules about how wide you can make your tires.

Good; modern wheels are just so unnecessarily large and wide. Smaller wheels with fatter tyres make for a more comfortable driving experience. It’s amazing that, in general, consumers have opted for larger wheels which are not in their own best interests. And I don’t want to hear anyone say ‘smaller wheels and fatter tyres are ugly’; smaller wheels being made by makers today are deliberately made to look ugly, so that they can upsell you a higher-spec model for a few thousand $ more. Smaller wheels can be made to look good, and hopefully this change will encourage that.

agree with everything except tire width. wider tires are safer tires.

nuh unh the thicker tires look good!!!!! keep them!!!!! There are other ways that cars can compensate, skinny wheels alone aren't inherently dangerous. The i3 has some pretty dinky looking rollers but they don't make the car unsafe.

that car and those wheels are an absolute abomination

Wider tires are a death sentence in downpours/sleet/snow/ice. They can't punch through to a grippier layer beneath like a narrower tire can. They just float around on top of it instead.

I think I've seen motorcycles with wider tires than that.

They're not a death sentence, they just don't work as well. One thing, that doesn't happen very often even in the UK, is not an argument for narrower tires which will perform more poorly 90% of the time.

I can't wait for people to be driving with shopping cart thin wheels with garbage chinese gripless rubberband quality tier tyres

The unsprung weight savings of smaller wheels alone could improve fuel economy slightly, i would think. Wheels have become too gotdamn big. Bring back 15s and thicc sidewalls

Im sure he means with higher HP cars in general use. See RCR when you put 1000+ HP on an sedan with shopping cart tires.

you don't need front grip as much as you think, rear tires should be a bit wide, but not too much, specially on road cars

>having a greater surface area of tire doesn't mean you have a greater surface area of tire ok

Whats the fucking problem? All these 17inch+ wheels meld your ass cheeks to the pavement while the vehicle is in motion. I love 14-15inch wheels with a wider tire and in an RWD like my 300TD it holds the road effortlessly and floats like a cloud.

Is that a joke? https://en.wikipedia.org/wiki/Pressure Tyre contact patch area is fixed by tyre pressure and vehicle weight. It's independent of tyre geometry. This is not even high school physics. Nice zinger though

Yeah but no magic amount of pressure will make a pizza cutter hook like 12 inch wide slicks. On the same car with the same pressure, fucking imagine that, more rubber means more grip (and yes, presuming the backspacing and suspension geometry is taken account for). And the question is of the same car essentially, since the busybodies in the Uk are whining about rolling resistance and taller wheels hurting mileage. And frankly they can go stuff it because if they had their way we'd all be driving shit like this https://upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Reva_i_silver.jpg/1200px-Reva_i_silver.jpg

Still no

because the worst part about the gwiz is the tires, not the fact that its an oversized powerwheels that's allowed to share the road with semi trucks and is totally exempted from all safety laws thanks to archaic safety loopholes.

Wide tyres are terrible in the snow. I've been in a car with 225/45/17 tyres that failed miserably at driving in the snow, and a car with 205/40/17 which handled like it was it driving in the rain when driving in the snow. Narrower is far better in the snow as the weight of the car is focused on a smaller area meaning it can push through the snow to the tarmac underneath far better. Snow is also fairly common in a lot of areas of the UK. And generally if you put wider tyres on a car within reason, it will handle better. There's a reason why it's so common to fit alloys that are 20 or so millimetres wider than standard.

"reduce emission by 0.000000000000000000000000001%" "IT'S FUCKING MANDATORY OH YEAH" Tbh at this point apart from the mandatory autism bestowed upon the EU I'm declaring the UK a zone of severe autism

I know this is SH but for god's sake read the article people. Nobody is banning bigger wheels. The mileage and emissions tests are now taking place on real roads and with this new testing, the effect a tyre is having on the mileage is inherently included in the final test result. This article is just speculating that these more accurate results that favour more efficient wheels may lead consumers to buy those cars. It's also unlikely car manufacturers will switch to tiny unsafe tyres since that will show on their safety tests like stopping distance.