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I picked up my new Eos this weekend (from out of state) and drove it back -- what a hoot! -- but am not thrilled with the low-profile tires that came on it. I REALLY like the looks of the Velos 18-in wheels but would like to fit some more comfortable tires on it when these wear out. OEM size is 235/40-18; does anyone know if 235/45-18 will fit? It appears that they would since it only adds an inch diameter to the tire but I was curious if anyone has experience doing so. Thanks!
 

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Be aware that going to the 45 series tires will mess up your speedo reading. You should check with a wheel place to see if a calibration of some sort can be done. The other option would be going to 17 inch wit 45 series. If your not concerned about it then get the tires of your choice.
 

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Has anyone tried 245's instead of the stock 235's? I'm looking at buying a set of 18x8 Audi S5 replica rims and putting 245/40/18's on them but don't want to have width issues.
 

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hi bud, quick question. i'm planning on changing the rear tires from 235/45r17 to 245/45r17 and leaving the front stock 235. would that cause any issue?
 

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I came across this link which explains tire maths if you can be bothered to follow it, rather than listening to somebody elso who says they just did it.:( it doesn't tell you if a change from the oem spec. will be safe or not, but it does explain how you can check if your speedo calibration will change and by how much. There may be something that vcds diagnostics can do to compensate?

Tire sizes are very curious because the first 3 digit group is tyre width in metric mm, whereas the last 2 digit group is the rim diameter in inches. If you just change the first group (the width) as micael asks, you might think the speedo won't change? but the height of the tire then follows from the middle 2 digits which is a RATIO figure and for his question, the figure of 40 is the same.

My brain is too tired to work out all the different scenarios for you, but if you can follow this link you should be able to calculate the estimated speedo error. But note that doesn't tell you the tires are safe on your chosen rim!

https://www.blackcircles.com/general/tyre-size-calculator

I worked out the sums for micael - 235x40x18 change to 245 x 40 x 18 because many might think just the width has changed and all will be ok? The overall diameters worked out as 25.4 inches for the OE and 25.72 inches for the wider tire. If you did no electronic compensation, That would give a speedo/odo error of about 1.25% when <0.5% is recommended.

In this example there is no off the shelf (smaller) aspect height ratio that will give the same standing height for the wider 245 tire so the only option is to put up with the speedo error or see if diagnostics will compensate. If a rim and tire combination is used on other VAGs it is likely it will be in an electronic correction table accessible through diagnostics.
 

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Those can be considered 'standard'.

I just ran calculations on tire/rim options for the 2007 2.0TSI: Smallest to largest:wheel diameters (inches) were as follows:

25.31,24.9,25.07,24.33,25.4. I didn't calculate the % errors, but you can see all the diameters are close.

The OP question was what is the largest tire? Well, it seems if you don't want to start recalibrating the odo and speedo, whatever width you may think is larger, the overall height will have to be the same.
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https://www.blackcircles.com/general/tyre-size-calculator

I worked out the sums for micael - 235x40x18 change to 245 x 40 x 18 because many might think just the width has changed and all will be ok?
That's a good link, and I've learnt something today.

It's worth repeating, because it's not obvious (and I didn't know it, so I guess others may not either): the second number in a tyre specification is the percentage ratio of tyre height to tyre width, not an absolute measurement of height. :)
 

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We both learned the same thing! I always thought if the rim size was the same, more width just mean't more rubber on the road when in fact the height of the tread changes. Nothing seems 'absolute' in tire numbering until you do the calculation. It would be an easy task to set up a simple spreadsheet for this, based on the tire calculation link I posted.

Now when somebody posts up their choice for replacement fancy wheels, I'll wonder what tire sizes they are choosing? Have you seen anything in vcds 'instruments' to compensate the speedo and odo? I once had to replace an instrument panel in a GM vehicle. Took it to a Stealer and they coded it for my wheels and tires, then drove it their measured distance to see if the odo came out correct. Nowadays you could confirm dash display errors with GPS.
 

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For those looking for alternative tires and wheels, start with the specs on the wheel you want first and then go to Tirerack.com to look at the specs of possible tires that closely match the specs of the OEM wheel/tire combination of your car. My 2007 Eos has 16" wheels and 215/55-16 tires. The resulting tire height is 25.3" and that results in, according to Tirerack, 821 revolutions per mile. So whatever tire/wheel combination you choose should have roughly the same specs. Your selected wheel should also have the same offset as the OEM wheel.

The Tirerack site lets you select tire and wheel combinations and lets you see what they look like on your Eos, which includes the body color of your choice. Pretty cool!

Personally, I like the stock look on my cars and I choose my tires (on all of my vehicles) based on the tire's performance in varying weather conditions. For many tires offered by Tirerack, the site provides extensive user reviews so you can gage which tires perform best: comfort, noise, responsiveness, and traction in rain, snow, and ice.
 

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Tyre size change speeds

For the record we checked the speedometer against the sat nav speed to see how much difference the tyre sizes might make and it shows a differential at 60 of 2.8 miles per hour slower on speedo than its actually doing, british speed cameras allow a 10% dif for inaccurate speedo calibration so no worries. You have to make a drastic change to see any difference.
 

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We went 19 inch Ispiri`s and fitted 265/35/19 rear with 245/35/19 front,even with TDI rear springs and adjustable coil-overs in front nothing touch`s
What width are your wheels?
Mine are 19x9.5" (-44ET) with 235/35's and I want to go 235/40 however am not sure about fitment.
 

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I run 225/45/18, which is about 1" taller than the 225/34/18 that is recommended. No issues with rubbing at all.
 
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