Wheel and tyre sizes

[Hawk]

My A6 Allroad has 20” wheels, I would like to change them for 18”. Does the offset need to be exactly the same?

[Magnet]

Hello Roger,

Many thanks for being in touch with the forum. 

‘Downsizing’ wheels is a fairly rare choice, but understandable in my book, if you are looking to improve the ride quality. Downsizing by two inches is a fair decrease though, 

Having said that, I guess you appreciate that the tyre profile will need to be increased to ensure the outside diameter of your proposed 18 inch wheel + tyre, will be equal to that of your current 20 inch. 

One other point - you will need to check if 18 inch wheels were listed as an option on your model year. If so, no problem, but if not, you will need to inform your insurers that you have fitted non-standard wheels. 

Appreciate the above does not answer your question about off set, but I would expect that if 18 inch wheels were an option then they are likely to be a straightforward fit. Of course, if you are thinking of aftermarket wheels then this information is of importance. 

Kind regards,

Gareth. 

[beemerboy9]

As a rough guide, the offset should be within 5mm of the original. Beyond that and one is changing the steering geometry, but I have no idea whether you would feel that through the power-assisted steering.

I have moved from a set of 20" to set a set of 17" Audi wheels - in other words an extra 1.38 inches (up from 3.5" to 4.88") of tyre sidewall. I feel that the smaller tyres give a lesser thump when traversing potholes, beside being less vulnerable to kerbing. The improvement may be greater on your Allroad with air suspension. The wheel/tyre combo was purchased from eBay seller "germanwheelsdirect" in Northern Ireland.

The 20" wheels look fantastic (and are great for the showroom guys), but I am sure the Audi engineers intended the A6 to ride on 17" or 18" wheels. 

[Chris jenkins]

On 12/31/2020 at 5:01 PM, beemerboy9 said:

As a rough guide, the offset should be within 5mm of the original. Beyond that and one is changing the steering geometry, but I have no idea whether you would feel that through the power-assisted steering.

I have moved from a set of 20" to set a set of 17" Audi wheels - in other words an extra 1.38 inches (up from 3.5" to 4.88") of tyre sidewall. I feel that the smaller tyres give a lesser thump when traversing potholes, beside being less vulnerable to kerbing. The improvement may be greater on your Allroad with air suspension. The wheel/tyre combo was purchased from eBay seller "germanwheelsdirect" in Northern Ireland.

The 20" wheels look fantastic (and are great for the showroom guys), but I am sure the Audi engineers intended the A6 to ride on 17" or 18" wheels. 

I’m having issues with my tyres on my Audi A7 Black Edition 21 inch had brand new tyres when I bought the car last year & have already had to shell out for two sets of tyres on the car the car had Dunlop super sport tyres on the car has anybody else had problems with. Dunlop tyres on there A7 

Can anybody tell me what tyres were originals put on car as I’ve been to Audi main dealer & they are telling me either Continental tyres or on newer A7 they are fitted with Bridgestone tyres would like help & your opinion pleas e

[beemerboy9]

Assuming that your wheel alignment is spot-on and that you are running at the correct pressures, then Michelin usually give the longest life. Pilot Sport 4 probably with a XL 101 load factor. 

How would you describe your car usage (high mile commuting etc.) and driving style?

[Chris jenkins]

Driving style just social & domestic as I have retired from work use the A38 in Devon from time to time to go to Plymouth or Exeter audi Plymouth checked wheel alignment & yes tyre pressure all correct according to Audi tyre pressure gage inside door .I have had other Audi A7 owners contact me to say Dunlop have a major problem with the sports max tyre & I have printed off all comments & sent it to Dunlop Goodyear as they have known about this problem for a while from what other drivers have told me .Tyres have been sent back to Dunlop Goodyear for tests in Germany & a letter from Mitchell Deever with Complaint letter attached 

Will let you know how I get on when I receive a reply I’m going back to what I know Michelin tyres 

[Stevey Y]

Hi Gents, I just thought I would throw this in.

Many years ago I bought a Mondeo Titanium x Sport as my third cab, this was sporting 19 inch wheels with 40 series tyres which even though branded tyres they wore like there was no tomorrow, factor in the accelerated puncture occurrence and it was a recipe for bankruptcy, I was only getting about 4k on the fronts and 8k on the backs without punctures.

I finally bit the bullet and bought some 16 inch wheels and tyres from my local tyre dealer, the wheels were genuine Ford off of a B Max I found a site on the net that gave the formula for tyre size to bring it up to the same rolling radius as the 19 inch wheel, anyway I engaged the help of one of my mates to help change the wheels we were a subject of fascination of one of my neighbours a German teacher at the local senior school called Gerhardt, he came over and asked what we were doing and when I explained he replied excellent!, it transpires he was a powertrain engineer at Wolfsburg for fifteen years his speciality was wheel and tyre combinations.

He went on to say he had tested every wheel and tyre combination known to man on just about every model VW produced, he explained that as long as you use OE wheels the offset is the same its only the rim size/width that changes, economy vehicles use smaller width tyres and rims as this helps with fuel consumption due to the lower rolling resistance of the tyres, we then go to larger heavier vehicles that use a wider profile tyre but may still use a 16-17 inch wheel. he ends up going into his house to get some scales so we could weigh the 19in rims and tyres against the 16in wheel and tyres, it was a marked difference between the two the 19in combination weighed 5kilos more than the 16in combination, he then said can you imagine how much extra energy is used to turn the extra weight and increased rolling resistance, you will now get extra MPG, he was right about another 8 miles per gallon and the added benefit was no more tram lining on uneven roads and better still no more aquaplaning in heavey rain as well as only occasional punctures.

I had to ask the question as to why they make these massive wheel/tyre combinations, he replied its what people want they think bigger is better, its not and sited the Mercedes E Class estates and saloons which were produced right up to the late nineties with 15-16 inch wheels and 70 series tyres with no compromise to the handling, as long as you use a minimum of 101 xl tyres you want have a problem and the tyres are cheaper and wear wise probably double the milage even on mid range tyres

[Meow]

Big wheels, or "Stupid-Wheels" is one of my pet hates. 

Marketing led and misunderstood by many consumers.

Depending on the make/model it can spoil things in at least two ways when it comes to choice.

1) New cars. Makes you avoid a better value higher spec'd variant because you are forced with that to take big wheels and low profile tyres. You can often get round it by taking a lower trim variant and piling on the options, but that is an expensive way to approximate to the higher spec variant, purely to avoid the Stupid-Wheels. I do wish manufacturers ( or often as it is, a country's importing company ) would just let the consumer decide if they want those sort of wheels and not think they know best for us, forcing it to automatically come with the higher general spec.

2) The available range of used cars. Again the higher spec variants suffering from Stupid-Wheels but also, the tendency for people to "upgrade" their wheels anyway on lower variants, often not realising the implication for noise and ride. Its so frustrating in browsing lists of available models, to find so few with sensible wheels. And you often end up missing out on a well spec'd car because of your wish to avoid Stupid-Wheels.

 

Audi aren't the worst for forcing Stupid-Wheels, compared to Mercedes for example, but I do get irritated in seeing things like "Black Edition" and the S line dominate people's choices and thus what's available in for sale lists. 

A related thing that really annoys me is the way functional options and upholstry/trim choices can be denied on a lower variant. But to take the higher variant would mean accepting the Stupid-Wheels. I wish manufacturers would just let people take a higher spec'd variant but leave people to make their own choices when it comes to wheels. 

By the way Jaguar actually allow buyers to 'downgrade' their wheels. I wish Audi, Merc and Skoda would do the same !

 

[beemerboy9]

28 minutes ago, Meow said:

Big wheels, or "Stupid-Wheels" is one of my pet hates. 

Marketing led and misunderstood by many consumers.

Depending on the make/model it can spoil things in at least two ways when it comes to choice.

1) New cars. Makes you avoid a better value higher spec'd variant because you are forced with that to take big wheels and low profile tyres. You can often get round it by taking a lower trim variant and piling on the options, but that is an expensive way to approximate to the higher spec variant, purely to avoid the Stupid-Wheels. I do wish manufacturers ( or often as it is, a country's importing company ) would just let the consumer decide if they want those sort of wheels and not think they know best for us, forcing it to automatically come with the higher general spec.

2) The available range of used cars. Again the higher spec variants suffering from Stupid-Wheels but also, the tendency for people to "upgrade" their wheels anyway on lower variants, often not realising the implication for noise and ride. Its so frustrating in browsing lists of available models, to find so few with sensible wheels. And you often end up missing out on a well spec'd car because of your wish to avoid Stupid-Wheels.

I agree with most of the above. What you forget to say is the the Stupid Wheels come also with Stupid firm and lowered Suspension.

Yes, my second-hand A6 Avant SE came with 20" alloys which thumped loudly over poor surfaces. I couldn't wait to get a nice set of 17" wheels and 55 section tyres on it. The big wheels I will keep because they will add hugely to the desirability/resale value at trade-in time.

My mind is boggled by the number of people who use their cars as an art form. I admit that some of the lowered cars look amazing, but I do wonder how practical they are.

The Germans have got it right. They buy a base car and everything is an extra. 

 

[Meow]

Yes and thank you for pointing out the typical accompanying trait of suspension differences.

I'd even avoid the very popular S line for this reason. Ease of access is a thing and so is clearance over speed bumps beyond ride generally.

Its a shame though, as the stylistic bodywork differences and I think interior trim differences also are nice. Plus certain options seem to be denied you on the base spec. I wish car companies wouldn't do this !  Unfortunately most buyers are tempted by the looks of the S Line or Black Edition specs and thus when you are looking at a list of available cars, the standard or base variant are few and far between and all the more so after you filter for colour/upholstry, miles etc.

[Chris jenkins]

Thanks for the information I’ve done some investigating myself & found out that Dunlop Goodyear when making 19 & 21 inch tyres used the Wrong Compound tyre Rubber mix that’s what’s wrong with these tyres nothing to do with size But here’s the Best bit after Bbc watchdog found out about this problem The Manufacture Did Absolutely Nothing No Recall on said tyres Why was this I wondered probably didn’t Want to Refund the Customer. So Stay We’ll clear of these Dunlop GT Maxxx tyres there Not Cheep & Don’t last . 

I got Geometry Of wheels checked

& the tracking & balancing all came back with perfect reports So it’s the tyre Not the wheel Size 

[Stevey Y]

Hi unfortunately the fact remains that wider bigger wheels wear tyres a lot quicker than say smaller wheels with higher ratio tyres as because of the appalling roads in this country the lower profile tyre has nowhere to go when rapidly compressed so it either deforms to absorb the impact which causes severe stress to the tread area or bursts and hammers the rim, this negates the whole point of the tyres being pneumatic and makes the tyre manufacturers a small fortune which recoups some of the money they had to spend to get the car manufacturer to use their tyres.

Steve.