Can l change tyre profile size...?

[........]

Quick question my wee mums A1 has 225/35/18 fitted to it but needs the 2 front tyres replaced asap l am in the train of thought to change them to 225/40/18
Reasons being

The ride quality is intolerable with a 35 profile
The price of 225/35/18 are a rip off they are actually the same price as my S3's 235/35/19 and in some cases brand dependent even more expensive car has only covered 6700 miles in 3 years and the Conti's are ******** already dreadful tyres had them on my previous S3

 

[Peter Peter]

Quick question my wee mums A1 has 225/35/18 fitted to it but needs the 2 front tyres replaced asap l am in the train of thought to change them to 225/40/18
Reasons being

The ride quality is intolerable with a 35 profile
The price of 225/35/18 are a rip off they are actually the same price as my S3's 235/35/19 and in some cases brand dependent even more expensive car has only covered 6700 miles in 3 years and the Conti's are ******** already dreadful tyres had them on my previous S3

Depends of your alloys J size.. But I say definitely you can it is only 5mm more
Check this : https://www.wheel-size.com/size/audi/a1/

 

[pburv]

Quick question my wee mums A1 has 225/35/18 fitted to it but needs the 2 front tyres replaced asap l am in the train of thought to change them to 225/40/18
Reasons being

The ride quality is intolerable with a 35 profile
The price of 225/35/18 are a rip off they are actually the same price as my S3's 235/35/19 and in some cases brand dependent even more expensive car has only covered 6700 miles in 3 years and the Conti's are ******** already dreadful tyres had them on my previous S3

Does this help you out buddy?
225/40-R18 vs 225/35-R18 Tire Comparison - Tire Size Calculator | Tacoma World

 

[Potterswheel]

If you change the aspect ratio of your tyres you will directly affect your gearing by changing the rolling radius. Going from 35 - 40 % aspect ratio (not width !!! this is NOTHING to do with your wheel size!) will increase your rolling radius therefore lower your gear ratio, whilst for your mother this may not be a bad thing it will definitely involve slipping the clutch more on take off but lower the rpm at cruising speeds , again for your mum maybe not a bad thing!

There are many web pages which will calculate this for you and draw images of the changes for you, but at the end of the day it all comes down to feel.

One good thing, is that a higher side wall will protect the rims a little.

In my experience the ride in all A1's is go-kart like.

 

[........]

Cheers guys thanks for the confirmation l am just going to go with the 40 profile

 

[45bvtc]

Quick question my wee mums A1 has 225/35/18 fitted to it but needs the 2 front tyres replaced asap l am in the train of thought to change them to 225/40/18
Reasons being

The ride quality is intolerable with a 35 profile
The price of 225/35/18 are a rip off they are actually the same price as my S3's 235/35/19 and in some cases brand dependent even more expensive car has only covered 6700 miles in 3 years and the Conti's are ******** already dreadful tyres had them on my previous S3

I ran 225/40/R18 (92Y) XL (Extra Load) Continental Sport Contact 5 tyres on 18-inch 7.5J ET39.5 OEM Audi 5-spoke Rotor wheels on our 185bhp A1 with no problem and yes it did improve the ride. Tyre pressures were: 37psi front and 31psi rear

 

[........]

If you change the aspect ratio of your tyres you will directly affect your gearing by changing the rolling radius. Going from 35 - 40 % aspect ratio (not width !!! this is NOTHING to do with your wheel size!) will increase your rolling radius therefore lower your gear ratio, whilst for your mother this may not be a bad thing it will definitely involve slipping the clutch more on take off but lower the rpm at cruising speeds , again for your mum maybe not a bad thing!

There are many web pages which will calculate this for you and draw images of the changes for you, but at the end of the day it all comes down to feel.

One good thing, is that a higher side wall will protect the rims a little.

In my experience the ride in all A1's is go-kart like.

She has kerbed the wheels several times... they are 5 wing arm design same as my S3 but in 18s

 

[........]

I ran 225/40/R18 (92Y) XL (Extra Load) Continental Sport Contact 5 tyres on 18-inch 7.5J ET39.5 OEM Audi 5-spoke Rotor wheels on our 185bhp A1 with no problem and yes it did improve the ride. Tyre pressures were: 37psi front and 31psi rear

View attachment 216636

You still got Bluey....??love that colour and the car

 

[Peter Peter]

Guys I have to ask
I had small accident. with my A3 quattro.
I unfortunately went through massive pot hole and it destroyed my tyre and maybe even shocker? It was quite massive bang with front left wheel
So, I have purchased used 2x 245 35 R19 tyres, but I have 2x 235 35 R19 ones. And now, I don't know which size should I put on the back and which in the front ??
I had installed 245's on the front on Thursday but I don't know if it was the bad road or what, I felt sort of vibrating but not massive maybe it was just bad road I have no clue. So I swapped wheels and now I have 245 ones on the rear and 235 front .. Do you think it is okay ? I haven't been on motorway yet to test but just around the town and don't know the difference of driving .. Please check pics of comparison of the wheels

 

[Potterswheel]

You cannot run mixed aspect ratio tyres on a quattro, even if you have uneven wear it upsets them - you will wear the larger aspect ratio out! you are supposed to rotate your tyres front to rear every 12 months.
The tyre dealer should have told you this.
You will either have to see if your friendly tyre dealer will have them back - 0r buy two more for the the other end.
Read my previous comments on changing the aspect ratio of your tyres before you make your decision either way.

 

[45bvtc]

You still got Bluey....??love that colour and the car

Thank you and yes 'we' have...

​

 

[........]

Thank you and yes 'we' have...

View attachment 216654 ​

Am Glad very unique car indeed

 

[Peter Peter]

You cannot run mixed aspect ratio tyres on a quattro, even if you have uneven wear it upsets them - you will wear the larger aspect ratio out! you are supposed to rotate your tyres front to rear every 12 months.
The tyre dealer should have told you this.
You will either have to see if your friendly tyre dealer will have them back - 0r buy two more for the the other end.
Read my previous comments on changing the aspect ratio of your tyres before you make your decision either way.

I just went for drive test on motorway while ago and the ride was perfect no any problems then I tried acceleration from stop and damn I could only now feel the REAL rear pull for first time I felt massive quattro push from the back :O It had perfect grip.

It has nothing to do with wear I have purchased used ones with 6.5 tread and my old has maybe 5? And yes I DID swap the wheels after one year when I had 235 35 all round.. But I purchased 2x for £95 as I really didn't want to spend 85 on brand new one when I can have 2x but yes I realised after that I messed up aspect ratio ... I supposed to buy 245 30 not 35 damn... I know bought on ebay so no they are not going back paid £70 for tyres and £25 delivery. No any tyre dealer fault they only did what I told them put 245 ones on wheels and balance them. I still have third 235 35 as spare...

 

[45bvtc]

Am Glad very unique car indeed

Thank you again and enjoy:

​

Please excuse the single-bucket wash equipment

 

[Peter Peter]

Thank you again and enjoy:

​

Please excuse the single-bucket wash equipment

How about that A2 ? you could do some tuning on it

 

[........]

Thank you again and enjoy:

​

Please excuse the single-bucket wash equipment

Am a one bucket man myself mate....2 bucket thing is pointless plus more work same result

 

[Potterswheel]

its up to you, the big ones will wear out!!!!

 

[45bvtc]

How about that A2 ? you could do some tuning on it

Great car for sure, Peter, the A2. But the A1 replaced the A2 and the SQ5 replaced the A1 - and we see nothing to replace our Bi-TDi SQ5, just a 100% 'complete' machine for us...

 

[Peter Peter]

its up to you, the big ones will wear out!!!!

How fast? Even if they are on the back??? The wheels swap from the front to back - back to front is done on only becuse fronts wears faster.
Now the 235 ones which has 5mil tread are on the front and 245 ones with 6.5 mil on the back.
I drive to work max 70-75 to save fuel... I had 235 ones since 2019 and they still going .

 

[Peter Peter]

Great car for sure, Peter, the A2. But the A1 replaced the A2 and the SQ5 replaced the A1 - and we see nothing to replace our Bi-TDi SQ5, just a 100% 'complete' machine for us...

Same A2 on mine street Shame audi discontinued this.. it could be nice smart audi car today model...

 

[A3SLine2014]

You cannot run mixed aspect ratio tyres on a quattro, even if you have uneven wear it upsets them - you will wear the larger aspect ratio out! you are supposed to rotate your tyres front to rear every 12 months.
The tyre dealer should have told you this.
You will either have to see if your friendly tyre dealer will have them back - 0r buy two more for the the other end.
Read my previous comments on changing the aspect ratio of your tyres before you make your decision either way.

Some bright spark told me I should rotate my tyres when I had one of my Mercedes and he thinking he knew everything said I was wrong when I told him I have different tyres front and rear....

Best tyres I have had are Riken UHP's. Treadwear was 580 and lasted ages on my previous Mercedes and replaced a set of Primacy's. That car i had continentals and Michelin on it and the Riken's just felt better. I am replacing the set of Potenzas on my a3 with the Rikens when they've worn

 

[Peter Peter]

Some bright spark told me I should rotate my tyres when I had one of my Mercedes and he thinking he knew everything said I was wrong when I told him I have different tyres front and rear....

Best tyres I have had are Riken UHP's. Treadwear was 580 and lasted ages on my previous Mercedes and replaced a set of Primacy's. That car i had continentals and Michelin on it and the Riken's just felt better. I am replacing the set of Potenzas on my a3 with the Rikens when they've worn

Try Blacklion bu66 much better..
https://www.tyrereviews.com/Tyre/Riken/Riken-UHP.htm
https://www.tyrereviews.com/Tyre/Blacklion/Champoint-BU66.htm

 

[A3SLine2014]

My dad has a diesel A2 220000+ miles on it no issues maintained by him.

 

[A3SLine2014]

Google willitfit and its a site you put in current wheel/tyre combination and ones you want to fit and will tell all with calculations

 

[Potterswheel]

Guys, you are mixing up width with rolling radius, some cars - particularly supercars with a rear mounted engine have bigger with tyres on the rear to take the weight, they are designed that way and may or not be 4 wheel drive (even if Quattro is not 'fully' 4 wheel drive)
Designed properly by someone who understands what they are doing, you can have different width tyres with the same rolling radius by changing the aspect ratio, the same width tyre with different aspect ratio cannot have the same rolling radius - it is just maths and is physically impossible,
If you have the same width tyres on front/rear (god forbid you are mixing them left / right! because some bloke down the pub said it was ok!) with different aspect ratios the higher aspect ratio tyre will effectively be trying to cover more distance per revolution than the lower aspect ratio tyres and thus wear out.

If you mix aspect ratios front/rear you are going to wear your tyres and long term damage/wear out your car.

 

[Potterswheel]

My dad has a diesel A2 220000+ miles on it no issues maintained by him.

what?????

 

[Peter Peter]

Guys, you are mixing up width with rolling radius, some cars - particularly supercars with a rear mounted engine have bigger with tyres on the rear to take the weight, they are designed that way and may or not be 4 wheel drive (even if Quattro is not 'fully' 4 wheel drive)
Designed properly by someone who understands what they are doing, you can have different width tyres with the same rolling radius by changing the aspect ratio, the same width tyre with different aspect ratio cannot have the same rolling radius - it is just maths and is physically impossible,
If you have the same width tyres on front/rear (god forbid you are mixing them left / right! because some bloke down the pub said it was ok!) with different aspect ratios the higher aspect ratio tyre will effectively be trying to cover more distance per revolution than the lower aspect ratio tyres and thus wear out.

If you mix aspect ratios front/rear you are going to wear your tyres and long term damage/wear out your car.

Yeah man but this mixing is not like come crazy difference like in supercars.. I didn't put rear tyres width like 325 or 315 etc, but just only one 1cm wider
And am pretty sure I don't have huge difference .. And no no any some ''bloke'' said in pub it is ok , pubs are shut and I don't go in such stinky ,dirty , carpet sticky places . Here is comparison and very minimal difference in rotating radius . Please check pic below
Thnx

 

[Potterswheel]

As I said it is just maths, the answer is there in black and white, assuming the higher aspect ratio tyres are on one axle and you drive the car 1 mile then that axle will attempt to travel a distance equivalent to 12 turns more, if each rotation is 80.9 inches (what is an inch?) that makes 970.8 inches more and that is coincidently 12 feet! so every mile you drive the axle that the higher aspect ratio tyres are fitted to will try to travel almost the length of the car more. Now do 100 miles!!!!!

Effectively you are wheel spinning everywhere you go.

The key point here is that we are pseudo 4 wheel drive and the hubs are driven at the same speed, the diameter of the wheel/tyre determines the distance covered per revolution. On a 2 wheel car the only effect would be to increase / decrease ride height.

nuf said........

 

[Peter Peter]

As I said it is just maths, the answer is there in black and white, assuming the higher aspect ratio tyres are on one axle and you drive the car 1 mile then that axle will attempt to travel a distance equivalent to 12 turns more, if each rotation is 80.9 inches (what is an inch?) that makes 970.8 inches more and that is coincidently 12 feet! so every mile you drive the axle that the higher aspect ratio tyres are fitted to will try to travel almost the length of the car more. Now do 100 miles!!!!!

Effectively you are wheel spinning everywhere you go.

The key point here is that we are pseudo 4 wheel drive and the hubs are driven at the same speed, the diameter of the wheel/tyre determines the distance covered per revolution. On a 2 wheel car the only effect would be to increase / decrease ride height.

nuf said........

Man you like astrophysicist or some space astronaut calculation expert for just some non important tyres in life. If you want precise calculations go to astrophysicist or medicine or science to do extreme measurement not on some used budged tyres man Which will make difference roundabout minus 6 months of total wear... Like I said had 235 since summer 2019 and now they have 5mm so another 2 years until completely worn and for 245 ones not total 4 years as they have 6.6mm so I will give them 2 years .. plenty time to save money for new ones.

No need plenty exclamation marks I understand I purchased wrong tyres so next time I will go 245 35 R19 all round ¯\_(ツ)_/¯

Edit: Like you said '' quatro is not real quattro'' don't know what you meant by that but Audi makes rear push adaptive .. In efficiency mode accelreation is done only with front wheels if you step on the gas fully rear quattro will engage straight away which I don't do .. full quattro will enable when you change to comfort or auto or dynamic and above 70 -70mph .. So if I travel in town slowly 30mph rear wheels are dragged by front wheels ...

 

[Potterswheel]

Here's a thought; (no calculations involved)

You are on ice, one end of you car is already effectively wheel spinning, and you accelerate

did someone say donuts????? (4 question marks)

 

[AlS3BE]

Man you like astrophysicist or some space astronaut calculation expert for just some non important tyres in life. If you want precise calculations go to astrophysicist or medicine or science to do extreme measurement not on some used budged tyres man Which will make difference roundabout minus 6 months of total wear... Like I said had 235 since summer 2019 and now they have 5mm so another 2 years until completely worn and for 245 ones not total 4 years as they have 6.6mm so I will give them 2 years .. plenty time to save money for new ones.

No need plenty exclamation marks I understand I purchased wrong tyres so next time I will go 245 35 R19 all round ¯\_(ツ)_/¯

Edit: Like you said '' quatro is not real quattro'' don't know what you meant by that but Audi makes rear push adaptive .. In efficiency mode accelreation is done only with front wheels if you step on the gas fully rear quattro will engage straight away which I don't do .. full quattro will enable when you change to comfort or auto or dynamic and above 70 -70mph .. So if I travel in town slowly 30mph rear wheels are dragged by front wheels ...

I think potterswheel is giving some sound advice by the way. No need for the sarcasm.
The other thing you are forgetting about is that your abs, traction control, esp etc are designed to work with certain tyre sizes and tolerances for tyre wear. By having different size tyres this will have an adverse effect on how it will behave in situations where you are relying on these electronics to do its thing with the potential of causing an accident and endangering the public.

anyway back On Topic guys.
@jassyo06 here are the numbers if you are interested. You can tell your mum to drive faster than the Speedo

 

[Peter Peter]

I think potterswheel is giving some sound advice by the way. No need for the sarcasm.
The other thing you are forgetting about is that your abs, traction control, esp etc are designed to work with certain tyre sizes and tolerances for tyre wear. By having different size tyres this will have an adverse effect on how it will behave in situations where you are relying on these electronics to do its thing with the potential of causing an accident and endangering the public.

anyway back On Topic guys.
@jassyo06 here are the numbers if you are interested. You can tell your mum to drive faster than the Speedo
View attachment 216687

I know, please don't talk about some accidents by choosing 1 cm different tyre.. Rather if someone would talk about destroyed roads and massive potholes which creates more and greatly massive risk of an accident on the roads ! And yet nobody care pot holes not repaired for several years no one give a damn if some car trips over and create an accident. Just now I reported massive pot hole damage which destroyed my tyre and almost the wheel and maybe even shocker which I will have to go to garage to check !

 

[Potterswheel]

Thanks @AlS3BE, and as you said I was not trying to be smart.

43 years working for a tyre manufacturer does this to you, you would not believe how much effort people put in to make these things the same size and stay that way

Question; what sort of web site uses POKE for offset? (one question mark)

 

[Peter Peter]

Thanks @AlS3BE, and as you said I was not trying to be smart.

43 years working for a tyre manufacturer does this to you, you would not believe how much effort people put in to make these things the same size and stay that way

Question; what sort of web site uses POKE for offset? (one question mark)

I am not saying smart or something but I wanted to know ''real world'' or real using rather than calculations which makes you to see numbers differences and then it only scares you off but real usage differences are minimal ..
What about tyre stretching ? even worse and massively dangerous, yet everyone praising it not demonetising it or saying you shouldn't do it only accepting it.. I have slightly different wheels and now I am bombarded ; what you done, you wrong , that's bad , that's unacceptable..
Am going to ask german audi technicians, what they will say .

 

[AlS3BE]

Thanks @AlS3BE, and as you said I was not trying to be smart.

43 years working for a tyre manufacturer does this to you, you would not believe how much effort people put in to make these things the same size and stay that way

Question; what sort of web site uses POKE for offset? (one question mark)

I don’t need to work 40 odd years in the tyre industry. Just a bit of common sense. I just don’t d1ck about with tyres and brakes. That’s my number 1 golden rule in any of my cars, new or old.

 

[45bvtc]

Them 4-tyres being your only contact with the road it's always best to have the best tyres - and that includes size/wear profile both front and rear- available ...

My pet hate being summer tyres in winter conditions and on this lovely sunny day here in Staffordshire @ 13.58 it's still only 6ºC and that for me is winter rubber whatever the size/profile...

 

[Meejaman]

As you seem to be deviating from an Audi wheel/tyre combination I would suggest you speak to your insurance company first.
You may wish to consider reducing the wheel size to 17” or even 16”, but keep to Audi specified combinations of wheel/tyre sizes. They may not care (Which will give you some comfort) it may be an easier conversation with the insurance company if you keep everything within the options available for that type of A1.

 

[FactionOne]

As I said it is just maths, the answer is there in black and white, assuming the higher aspect ratio tyres are on one axle and you drive the car 1 mile then that axle will attempt to travel a distance equivalent to 12 turns more, if each rotation is 80.9 inches (what is an inch?) that makes 970.8 inches more and that is coincidently 12 feet! so every mile you drive the axle that the higher aspect ratio tyres are fitted to will try to travel almost the length of the car more. Now do 100 miles!!!!!

Effectively you are wheel spinning everywhere you go.

The key point here is that we are pseudo 4 wheel drive and the hubs are driven at the same speed, the diameter of the wheel/tyre determines the distance covered per revolution. On a 2 wheel car the only effect would be to increase / decrease ride height.

nuf said........

Haldex won't like it. But nor will ABS (ESP, TPMS, Park Assist, loads of other systems...)

 

[Peter Peter]

Sorted... 245 35 R19 all round

 

[........]

Well i ended up getting 2 Bridgestone Potenza tyres with the 225/ 3518 tyre size £224 for 2 tyres not including fitting so £254 all in rip off