Wider tires on a 2.5i

[Waynerm002]

I recently purchased a set of stock 17 inch wheels from one of our members (thanks Chris!) and think the wheels look a little too narrow compared to what I had on the Audi A4 with the sport package (235/45-17). I like the aggressive look of the wider tires and from what I have been reading on different forums, more contact patch gives better performance in the dry.

 

My question though is, will a wider tyre have any significant impact on my fuel economy? Will the performance be much better than with the stock size? How much will the speedo be off if I was to go with a size of say 235/40-17? Will 225/45-17 be a much better compromise? I know I am asking a lot of questions but I want to get some response from folks that have tried these sizes and have experience with them. I believe the GT and 2.5i are about the same when it comes to the size of tyres they can wear. I may lower the car at some point so I want something that will work either way.

 

Please give pros and cons on your responses, thanks!

[Waynerm002]

No one has any info to share? I did look through the posts but wanted to get some opinions and I know a few of you track your cars and would probably be able to offer some info. I plan on keeping the stock 17s but wanted to get an idea on how much different the ride would be.

[Xenonk]

My question though is, will a wider tyre have any significant impact on my fuel economy? Will the performance be much better than with the stock size? How much will the speedo be off if I was to go with a size of say 235/40-17? Will 225/45-17 be a much better compromise? I know I am asking a lot of questions but I want to get some response from folks that have tried these sizes and have experience with them. I believe the GT and 2.5i are about the same when it comes to the size of tyres they can wear. I may lower the car at some point so I want something that will work either way.

 

Please give pros and cons on your responses, thanks!

 

-Impact on Fuel Economy = a little, depending on weight and actual size

 

-Performance Gain = since it's on a 7" wide OEM rim, it wont be much since the wider tire will give you sloppy side walls. The steering input might be slower in reaction time. If you went with a wider rim, then it would be beneficial and the handling gains are better. Weight is an issue as well when going with a wider rim.

 

-Speedo Calibration = those sizes listed are within +/- 2% error range. It wont be off by more than 2mph to 3mph.

 

-235/40/17 vs 225/45/17 = the 225/45/17 is the more obvious choice to have over the 7" wide rim you are mating it with. The 235 is a bit wide for a 7" wide, especially with 40% sidewall. The 225 sits more upright with the rim and has a a taller sidewall to protect the rim better from potholes and such.

 

-GT vs i = yes, the suspension geometry is the same.. you can put aftermarket GT coilovers on the 2.5i if you want. Same goes for sway bars and the sort.

 

 

Keefe

[Waynerm002]

Thanks Keefe! I can always count on you for some good info! Lately I have been testing the performance potential of the 2.5i and find that I will probably want to do acouple of things to sharpen up the ride but still keep it nicely damped with less body roll or nose diving. The main concern for me here is cost. I typically do a tire and brake upgrade along with suspension mods. Swithching to the A4 with sport package allowed me to just do brakes and tires (found out how much I needed those on a "fun run" with the Audi club, never want to experience that brake over heating syndrome again), which improved the performance a lot.

 

I am now getting comfortable with the 2.5i and feel that it compares quite well with the A4 1.8t performance wise. Wish it had 6 gears though, keep hitting the limiter at close to 80 in third, just about when it seems the car is hitting it's stride. Really loving this car now!

[Bretm1]

wayner,

 

 

funny you mention the more aggresive look of the 235/40 on the audi. i have a set of 235/45/17 from another car and after going through all of the different threads i thought that going fatter was no problem. it isn't but it is if you want to use your stock rims ( i have an 05 lgt ltd 5ea)

 

yesterday i had a garage stick the 235 45 17 onto my stock wheel. boy did it look nice, even though the wheel may be a little narrow. any how we stuckit on the front and lowered it and it hit the strut tower and inside of the wheel well when turned all of the way. it looked great, was tucked in nice etc. so it was kind of frustrating that it wouldnt work without an offset. i personally liked the beefiness of the 235 with the 45 mm /or 40 mm sidewall much like what we see on beemers audis and even the acura tl. i was kind of pissed that the subie would require offset rims and or spacers to achieve this due to the potential negative effects of some offset set ups-this is a performance car and i want the look to be there but functional, even with the wagon unlike the 5 series or 3 series bmw or the audi s4, it doesn't seem like we have the luxury of ust throwing the wheels on without adversely affecting something.

 

your 235/40 has a lower side wall, but the width is still there.

 

LET ME KNOW IF IT FITS (if your gonna try) ON A STOCK WHEEL WITHOUT RUBBING ANYWHERE .

 

i'll be kind of pleasantly surprised.

 

most of the reading i have done shows that going to 7.5 " aftermarket rims with only a 225/40/17 requires a 40(millimeter??? i think) offset.

 

to me going 10 mils bigger on the width coupled with the offset just plain is not worth it

 

All you experts out there please chime in. I've done a lot of reading but I still need the reassurance.

 

Can I stuff a set of 235's in there without fender rolling or heavy offsets????

 

doesn't really seem like it

 

I'll get the wheels if it works

[Waynerm002]

I plan on giving the 225/45 17s a try. Or maybe just stay with the factory size and get better tires. I have a road trip coming up and I don't trust these tires at high speed much. Although I have learned how to adjust my driving with them and brake earlier to bleed off some speed, then slow normally. I guess I got used to the cross drilled/slotted brakes and better pads on the Audi which would help to bleed off the speed without over heating the brakes.

 

The bigger contact patch is something I got to like on the German cars, plus a good suspension setup (factory sport package) which gets rid of the wheel gap.

[rc0032]

I plan on giving the 225/45 17s a try. Or maybe just stay with the factory size and get better tires. I have a road trip coming up and I don't trust these tires at high speed much. Although I have learned how to adjust my driving with them and brake earlier to bleed off some speed, then slow normally. I guess I got used to the cross drilled/slotted brakes and better pads on the Audi which would help to bleed off the speed without over heating the brakes.

 

The bigger contact patch is something I got to like on the German cars, plus a good suspension setup (factory sport package) which gets rid of the wheel gap.

I will sell you my USDM GT takeoffs

[Waynerm002]

What do you mean? If you are talking wheels, I already purchased and am currently running a set of LGT 17" wheels. From what I understand, the suspension on the GT is the same as the 2.5i. The car already seems low, but I would love to get rid of some of the wheel gap. Maybe summer before I can afford any kind of suspension upgrade.

[rc0032]

The US GT does not have the same suspension as the US i. The springs are the same rate but the struts are different. I also have a set of JDM GT springs. Combine these and it will remove some of the wheel gap and make the car handle better

[Edvig]

Keefe, the 2.5i comes with 16 x 6.5 in rims and 205 55 16 tires. A 7 in rim should allow him to go to a wide enough tire that would be a noticable performance upgrade...yes?

[Xenonk]

yesterday i had a garage stick the 235 45 17 onto my stock wheel. boy did it look nice, even though the wheel may be a little narrow. any how we stuckit on the front and lowered it and it hit the strut tower and inside of the wheel well when turned all of the way. it looked great, was tucked in nice etc. so it was kind of frustrating that it wouldnt work without an offset.

 

most of the reading i have done shows that going to 7.5 " aftermarket rims with only a 225/40/17 requires a 40(millimeter??? i think) offset.

 

to me going 10 mils bigger on the width coupled with the offset just plain is not worth it

 

All you experts out there please chime in. I've done a lot of reading but I still need the reassurance.

 

Can I stuff a set of 235's in there without fender rolling or heavy offsets????

 

doesn't really seem like it

 

I'll get the wheels if it works

 

 

Well, I didn't follow very well on your what you wanted exactly since you posted a lot of "I want this" vs "I dont want that to deal with" but I will try to guide you in the direction that may help.

 

First, let's clear up some things. Most tires are designed with an actual sectional width being very different. For example, a 225/45/17 Falken Azenis RT-215 is built wider than most 225/45 tires (in fact, it's built like a 245 almost). As for offsets, it's nothing but a number by itself. In order compare offsets, you need to know what rim width we are going to deal with. The offset there to help fit the wheel in the fender as optimal as possible. What may seem a "heavy" offset differences isnt really "a big" difference when you put the two wheels next to each other (since the mounting point didnt change much). If you look at the stock tire, it's really "IN" the wheel well, so there's plenty of room for offset difference (lower offset to push the wheel out some or to compensate the wider aftermarket rim). The offset is also there (when using the correct offset) will prevent pre-mature wheel bearing.

 

I am not sure what kind of 235/45/17 you crammed on the stock wheels, but it's very close to the point where you are rubbing not only the fender liner, but as well as the spring perch. Rubbing on the fender liner isnt a big deal, but the spring perch or fender lip itself is A LOT MORE important. If you want, you could buy a 5mm (1/4") spacer just to clear the front using stock rims. I wouldnt recommend that as there could be larger complications later that I have not done the homework on.

 

Your best bet is to actually buy a 17"x7.5" rim with a larger offset (say 42mm) rim and run as wide as a set of 245/40/17 tires. There's actually a lot that you can do and I have gone through enough rims to tell you that I have installed a set of 255/35/18s with a 18x8 rim (+51mm offset) and ran them daily in the streets of DC Metro-area.

 

If you want to go wide, go wide, as I know now that I can do a 18"x8.5" with a +45mm offset and put some 265/35/18 tires on my GT. Just use my wheel/offset/tire FAQ for re-assurance of what will work and what wont. If you still have questions about what works and what doesnt, just PM me or post a thread of your specific concern on the wheels/tires forum and I'll post accordingly.

 

Keefe

[dustinw]

....

i personally liked the beefiness of the 235 with the 45 mm /or 40 mm sidewall much like what we see on beemers audis .....

 

Just so you realize that the sidewall height is a percentage of the width, not a measurment in MM.

 

235/40 would have a sidewall that is 94mm tall

225/45 would have a sidewall height of 101.25mm tall

215/35 would be 75.25 (had that on my last car).

 

Anyhow a 40-45mm sidewall would be a very thin tire (that would be a 225/20)

[Xenonk]

Keefe, the 2.5i comes with 16 x 6.5 in rims and 205 55 16 tires. A 7 in rim should allow him to go to a wide enough tire that would be a noticable performance upgrade...yes?

 

 

Best off to get a 7.5" wide rim and 225/45/17s (+40mm to +54mm). Stock GT wheels (7" wide) can put on some 225/45/17s (that's what I run on my GT right now for autox school days and stock class Solo2 racing). 7" feels a little sloppy on the 225/45/17 sidewalls if the tires are not at autox pressures, so a 7.5" wide with a 225/45/17 is more ideal. If you want, a 8" wide rim with a +48mm offset can handle a 245/40/17.. that's plenty of rubber of you then and no rubbing issues either.

 

 

Keefe

[Bretm1]

Well, I didn't follow very well on your what you wanted exactly since you posted a lot of "I want this" vs "I dont want that to deal with" but I will try to guide you in the direction that may help.

 

First, let's clear up some things. Most tires are designed with an actual sectional width being very different. For example, a 225/45/17 Falken Azenis RT-215 is built wider than most 225/45 tires (in fact, it's built like a 245 almost). As for offsets, it's nothing but a number by itself. In order compare offsets, you need to know what rim width we are going to deal with. The offset there to help fit the wheel in the fender as optimal as possible. What may seem a "heavy" offset differences isnt really "a big" difference when you put the two wheels next to each other (since the mounting point didnt change much). If you look at the stock tire, it's really "IN" the wheel well, so there's plenty of room for offset difference (lower offset to push the wheel out some or to compensate the wider aftermarket rim). The offset is also there (when using the correct offset) will prevent pre-mature wheel bearing.

 

I am not sure what kind of 235/45/17 you crammed on the stock wheels, but it's very close to the point where you are rubbing not only the fender liner, but as well as the spring perch. Rubbing on the fender liner isnt a big deal, but the spring perch or fender lip itself is A LOT MORE important. If you want, you could buy a 5mm (1/4") spacer just to clear the front using stock rims. I wouldnt recommend that as there could be larger complications later that I have not done the homework on.

 

Your best bet is to actually buy a 17"x7.5" rim with a larger offset (say 42mm) rim and run as wide as a set of 245/40/17 tires. There's actually a lot that you can do and I have gone through enough rims to tell you that I have installed a set of 255/35/18s with a 18x8 rim (+51mm offset) and ran them daily in the streets of DC Metro-area.

 

If you want to go wide, go wide, as I know now that I can do a 18"x8.5" with a +45mm offset and put some 265/35/18 tires on my GT. Just use my wheel/offset/tire FAQ for re-assurance of what will work and what wont. If you still have questions about what works and what doesnt, just PM me or post a thread of your specific concern on the wheels/tires forum and I'll post accordingly.

 

Keefe

 

Keefe******(no need to reply unless of course you want to-i hate to have you spin your wheels when i should have read more first)

 

You are a good man. (you have given a lot of info-much appreciated) After that particular post, I have learned a lot by studying your tire sticky. I hope that doesn't get taken down anytime soon. I will need it when I make a move to a wheel tire package. Just as an FYI i tried sticking a dunlop sp9000 234/45/zr17 under the wheel well. It was indeed rubbing the spring perch.

 

I also admittedly did not realize how much of a difference there was in appearance with a 225/40/17 tire. It is not huge but it still has a "beefier" look than the stock 215's. Thats why I was beachin' about how I didn't think it was worth it blah blah blah. The "meantime" gameplan right now is to stick a set of decent all season/performance 225/40/17s on my stock rims. Then I will in time purchase a set of 245/40/18's performance tires with a nice set of relatively light weight wheels.

 

Thanks so much for taking the time to respond to this-on behalf of me and the whole forum.

 

Bret

[Bretm1]

Just so you realize that the sidewall height is a percentage of the width, not a measurment in MM.

 

235/40 would have a sidewall that is 94mm tall

225/45 would have a sidewall height of 101.25mm tall

215/35 would be 75.25 (had that on my last car).

 

Anyhow a 40-45mm sidewall would be a very thin tire (that would be a 225/20)

 

Thanks Dustin-I was just complaining to my wife that no one talks to me on the forum. I am in the 21st century with a cellphone, palmpilot and several other gadgets I don't really need but I am embarrassed to admit that this is the first forum of any kind that I have ever been on. (let laughter subside)

 

They didn't have a forum for my 1972 powder blue chevy vega 2 speed auto. I'm also embarrased that after working most of my young life in gas stations changing tires etc, that it never dawned on me that that second number these days is a percentage not a metric millimeter measurement. But back then we used letters like F60-15 etc. that I don't think I could even explain as I have a hard enough time remembering modern day stuff.

 

This forum has taught me a lot.