18" 17"? Does car wheel size matter?

[treet]

Whats the deal with car wheel size? We are currently looking for a car secondhand and the ads seem to emphasise that it has 18" wheels which is apparently better than the standard 17". The man at the garage didnt really seem to know beyond saying that larger ones look better. As these are only family car SUV/MPVs I am a little sceptical that it matters so what benefits would I get by going for the bigger wheels? Is there any difference in tyre cost etc?

Better MPG, the bigger the wheels the better your range

And usually dearer

Don’t think it work quite like that…

For larger wheels: Looks (subjective)

Against: Tyres are more expensive
Worse ride quality
Worse performance (more wheel and less tyre usually means heavier, so slower and fractionally worse economy. )

Usually larger rims have lower profile tyres which are easier to damage and more expensive to replace.

Some people think they look nicer so it’s a way to sell an ‘upgrade’ that’s fairly high margin.

Had a car with 18in wheels and sports suspension utterly fucking awful.

Personally the ride is far more important than the look.

17" isn't a 'standard' size though, unless you mean for that particular model. If a salesman is emphasising an upgraded wheel on any particular model he is just trying to show the car is 'better' than the factory standard for that trim. I think any difference re tyre price and wear and tear would be negligible. You can pay more for a top of the range 15" tyre than a budget 18" anyway.

Apart from an 18inch rim giving a harsher ride (looks better to the boy racers though), the larger the wheel (and less deep the tyre) the more chance of damaging the rim on potholes, kerbs etc.

My own vehicle (4x4) is occasionally fitted with 18inch rims but I wouldn't have them if you paid me and I have always run 16inch.

When I was looking at cars the fiesta was 16" and focus was 17". The costings were quite a bit different eg £30 per tyre for just above budget. If you want really good tyres then its a lot more. Multiply that by four wheels. Then depending on mileage multiply that amount by years. 18" sounds expensive when its all added together 😯

We had a car on low profile tyres and it cost us a fortune in changing them due to the crap on the road that punctured them. Fortunately we no longer have that car nor that commute on the shitty road.

Tremendous effort

as someone said, larger wheels are fitted with lower profile tyres so the overall size is the same

the benefit is looks. Bigger wheels look better (to most people)

the downsides are that the lower profile tyres usually cost a bit more, and their lower profile means the ride of the car may well be a bit harder. This means it’ll handle a bit better but feel harsher over bumps.

With regard to tyre cost, you need to check the exact size. A really common 18” tyre is likely to be cheaper than an unusual 17”.

Think about riding a bike - you have to pedal more on a bike with small wheels than you do with big wheels. It's the same for a car engine. It has to work harder (use more fuel) to turn small wheels.
You go further with big wheels for the same amount of effort (bike or car).

Racing cars and some sports cars used to need bigger wheels to fit the larger brakes that they needed. Bigger wheels then became “design language” meaning “sporty” and so became desirable.

The fact is though that in nearly every case now it’s a case of how it looks, as people want “sporty”. It comes with a major disadvantage as each model of car is designed for a given tyre radius. A bigger wheel therefore generally means a low-profile tyre (looks more like a rubber band round the wheel than a big ballon) which is awful for road noise and rude comfort.

Unless you really want the low-profile tyre look then save money and get the smaller wheels which you will probably like more.

No. Wheels+tyres add up to the same diameter. Bigger wheels need smaller tyres.

I don’t think you quite understand how it works.

That makes no sense at all. Even if there was a lower rolling circumference (there isn’t) it’d be very unlikely to be the case.

If they were a lower rolling circumference then you effectively shorten the final drive ratio and would use more fuel but that isn’t the case here.

The bigger the wheel, the lower profile of the tyre. What that means is the sidewall of the tyre is smaller. This means it stronger and more resistant to deflecting under load (i.e. cornering or braking), so the tyre maintains its shape and therefore contact (grip) better. You can corner faster and stop quicker, effectively.

It also means it resists deflecting when coming into contact with potholes, cats-eyes, speed bumps etc. So the ride is a lot more harsh, and the car is more likely to be skittish and jump about on the road when hitting a bump mid-corner, for example. This is compounded when fitted with firmer suspension, which cars with big wheels usually are.

And they cost more.

Cost is very much dependant on the exact size. There are plenty of 17” sizes which are more expensive than 18”. A 225/50/17 is more expensive than a 225/40/18 for example. If tyre cost is important then it’s essential you price up the exact tyre sizes in the same brand(a) as a comparison.

*So the ride is a lot more harsh, and the car is more likely to be skittish and jump about on the road when hitting a bump mid-corner, for example.

And the rim is more likely to crack if you hit a pot hole.

As my husband has just discovered.

Any difference in fuel consumption will be negligible. Basically, bigger wheels look cool but cost more when new, make the car’s ride worse and need more expensive tyres. Salesmen push them as an ‘upgrade’.

Smaller wheels are cheaper & more comfortable and need less expensive tyres but don’t look as good. I would always go for smaller wheels.

Hi. The larger rims, 18 inches in your case, would give a harsher ride, bumpy and bouncy. However the larger rims give better handling, so more enjoyable to drive. As for looks, more personal preference.
Unless you love driving or are Lewis Hamilton, the smaller rims and better ride quality is preferable in my opinion. The differences are often fairly marginal however.

It’d depend on gearing and cruising speed still.

It’d have exactly the same effect as shortening the final drive. Increased fuel consumption at any given speed.