Different tyre sizes front & rear

Dean Shirt

Registered User
Hi, first of all this is my first post as I have recently purchased a 2017 A4 avant S line tdi 190 (stronic)and I love it. However I have a query...... yesterday whilst cleaning my wheels I noticed that my rear tyres are a different size to my front. Rear 245/40/18 Front 245/45/18 is this meant to be? This car has been services with Audi all its life not that it matters but surely they will have also seen this? All the tyres are Pirelli. Would you raise this with the garage I bought it from? Any advice is welcome. Thanks in advance
 

Jsmills

Registered User
Should be the same front and back. The A4’s don’t do the differing size thing like the C Class does.

it could have been done for a few reasons:

error
Pursuit of comfort
All they had in and needed quickly
Save a few £

if it was from a main dealer I’d kick up a fuss. If not I’d just pay the £250 quid as it’ll probably be easier. Many would probably live with it but technically it could invalidate your insurance (unlikely) as they are the wrong size. The panel inside the drivers door will list the correct sizes so check which one but I think the 40’s are the correct pair.
 

Dean Shirt

Registered User
Should be the same front and back. The A4’s don’t do the differing size thing like the C Class does.

it could have been done for a few reasons:

error
Pursuit of comfort
All they had in and needed quickly
Save a few £

if it was from a main dealer I’d kick up a fuss. If not I’d just pay the £250 quid as it’ll probably be easier. Many would probably live with it but technically it could invalidate your insurance (unlikely) as they are the wrong size. The panel inside the drivers door will list the correct sizes so check which one but I think the 40’s are the correct pair.

Thank you for the comment, you are correct I have rang Audi and they advised it should have the 40s all round so the front have been replaced with the incorrect size. It wasn’t a main dealer I got this from. I have spoken with the garage I bought this from and he has told me it’s been through the inspection and mot and it has not been advised hence why they haven’t been changed. I think these have been on a while so could just run these until they need replacement. However I don’t know if these will cause any issues with the car? Thanks
 

Jsmills

Registered User
Don’t think it’ll do the car any harm, the speedo will be incorrect, as the 45,s are bigger the speedo will read slower than your actually going, I’d guess by 5% ish.
 

HMG1K

Registered User
Many would probably live with it but technically it could invalidate your insurance (unlikely) as they are the wrong size. The panel inside the drivers door will list the correct sizes so check which one but I think the 40’s are the correct pair.

Yep, yep, and yep ^^^^^

In the event of an accident, if your vehicle was to be inspected by an insurance company assessor; this is the 'gold' nugget the insurer will use to get out of paying out.

Unless, of course, your insurance is made aware of what would be deemed as a 'modification'.

If it was declared, it would have to be clear the rubber tyre size is different from manufacture spec, and not just a different design alloy of the same size and dimensions of the standard alloy for your car.
 

Dean Shirt

Registered User
Don’t think it’ll do the car any harm, the speedo will be incorrect, as the 45,s are bigger the speedo will read slower than your actually going, I’d guess by 5% ish.
Cheers mate, I will run them until they need replacing then. Then I can put the correct tyre on. I have found out they had been changed by national tyre around 12 months ago so there is no chance I can get them to swap them now 12 months down the line. As long as it’s not going to play havoc with my stronic box or suspension then I’ll be at ease
 

Dean Shirt

Registered User
Yep, yep, and yep ^^^^^

In the event of an accident, if your vehicle was to be inspected by an insurance company assessor; this is the 'gold' nugget the insurer will use to get out of paying out.

Unless, of course, your insurance is made aware of what would be deemed as a 'modification'.

If it was declared, it would have to be clear the rubber tyre size is different from manufacture spec, and not just a different design alloy of the same size and dimensions of the standard alloy for your car.
Agreed, I wouldn’t want that to happen. Seeing as I’ve just bought the car I don’t want to be spending another £350 for two new tyres but I don’t know where I’ll stand with the dealer.
 

jds_sg

Registered User
Agreed, I wouldn’t want that to happen. Seeing as I’ve just bought the car I don’t want to be spending another £350 for two new tyres but I don’t know where I’ll stand with the dealer.

If the potential insurance issue bothers you its perhaps best to get them changed, but there's no need to pay £350 for 2 tyres of 245/40 18" size if you shop around.
 

Dean Shirt

Registered User
If the potential insurance issue bothers you its perhaps best to get them changed, but there's no need to pay £350 for 2 tyres of 245/40 18" size if you shop around.
Thanks mate, on the new Tyre’s is their any I should stick to? I know Audi approve Pirelli and hancook however what do you guys use? Thanks
 

jds_sg

Registered User
There are quite a few threads on here discussing tyre types already, everyone usually has their favourite! From what I've seen on here the most popular brands seem to be Hankook, Goodyear, Michelin & Continental. Pirelli not so much...

But if you look at blackcircles.com as a start you'll find tyres from top brands available, such as Goodyear F1 Assy5 for £107 fitted for example.

And of course there are many other brands available at all price points.
 

smog c6

Registered User
If it’s not Quattro should be okay.

I would strongly advise you check with your insurance company if it is a problem. Certain insurance companies may view this as an invalidation of insurance if the tyre size isn’t an OEM option.
 
Hi Dean and congrats on the new purchase.
It's not right but the difference is tiny. 3.7% on rolling circumference/speedo. They all over-read so you'll have the more accurate one! Having said that there IS a difference between 17/18/19 inch wheel/tyre set ups that are all interchangeable so no worries there. You didn't notice visually, the dealer inspection is an irrelevance, but the car has passed an MOT with those tyres. I agree they are not dangerous and I'd challenge any insurer if it came to them disputing a claim. There are scare stories but insurers nowadays don't use irrelevant technicalities to avoid legit claims, there's enough real stuff to get their teeth into. What could the tyres add to causation?
100% will not play havoc with the suspension/gearbox etc. as it's not quattro. Do one for the environment and live with them.
 

Dean Shirt

Registered User
Hi Dean and congrats on the new purchase.
It's not right but the difference is tiny. 3.7% on rolling circumference/speedo. They all over-read so you'll have the more accurate one! Having said that there IS a difference between 17/18/19 inch wheel/tyre set ups that are all interchangeable so no worries there. You didn't notice visually, the dealer inspection is an irrelevance, but the car has passed an MOT with those tyres. I agree they are not dangerous and I'd challenge any insurer if it came to them disputing a claim. There are scare stories but insurers nowadays don't use irrelevant technicalities to avoid legit claims, there's enough real stuff to get their teeth into. What could the tyres add to causation?
100% will not play havoc with the suspension/gearbox etc. as it's not quattro. Do one for the environment and live with them.
Thanks for this comment mate makes much sense. I didn’t notice them visually at all and it drives how I would expect. Having never owned a Audi before it drives beautiful! Yes I’ll keep running them until I’m due the new ones. I may give the insurance the heads up just to cover myself. Thanks for the comment mate
 
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