[AP1toGDRev.G]

I have been looking into buy a used set of wheels, and two of the best sets of rims I have found both had 245/40s on and would not part them, so I had to pass...

I am not a fan of this size and I was just wondering why so many people tend to go w/ this size instead of a 235/40.



Oh, and ya I searched. But, if you can search better than me go ahead and point me in the right direction.

[KrazyKarl]

Some people like the way a little bulge looks

It can also help protect the wheel from mild curbage if you run a wider tire. I'm assuming these are 8" wide wheels...if they're 8.5" then 245s would have pretty straight sidewalls.

also, it'll be slightly taller than stock, so the speedo might actually end up being accurate instead of reading 3-5 mph high.

[AP1toGDRev.G]

^ I have your wingless trunk...Hahahah

I just do not think it is the ideal, size yet it seems so popular. Both wheels I looked into were 8.5 wide. It seems alot people think wider is "better", so they feel the need to put the widest tire that can "fit" on to get "max performance."

I do not like this size for the following reasons....

-worse gas mileage.
-softer/sloppier ride created by too much sidewall
-Speedo/odo thown off (where as a 235/40 would fix the oem probblem)
-decreases brake performance
-increase in unsprung wieght
-etc

I am trying to find the pros of this size compared to a 235/40.
The only way I would want to run a 245 would be in a 35, series which is not very commom.

[lackskill]

Originally Posted by AP1toGDRev.G

I have been looking into buy a used set of wheels, and two of the best sets of rims I have found both had 245/40s on and would not part them, so I had to pass...

I am not a fan of this size and I was just wondering why so many people tend to go w/ this size instead of a 235/40.



Oh, and ya I searched. But, if you can search better than me go ahead and point me in the right direction.

I run 245/40/18's because they were about the widest I could safely fit and the 3% difference at the speedo is not enough to deter me from having them. I don't really see the problem....

[lackskill]

Originally Posted by AP1toGDRev.G

^ I have your wingless trunk...Hahahah

I just do not think it is the ideal, size yet it seems so popular. Both wheels I looked into were 8.5 wide. It seems alot people think wider is "better", so they feel the need to put the widest tire that can "fit" on to get "max performance."

I do not like this size for the following reasons....

-worse gas mileage. not really. I get virtually the same mileage as I did stock.
-softer/sloppier ride created by too much sidewall as opposed to the 070 everything is soft. my RT615's are still plenty stiff...
-Speedo/odo thown off (where as a 235/40 would fix the oem probblem) this is just flat incorrect. A 235/40 is very close to the stock height, while a 245/40 is .7" taller than stock. 3% or ~2mph at 60mph difference.
-decreases brake performance marginally if at all. tire compound will have a much more profound difference than the slight weight difference. not to mention the larger contact patch of the 245.
-increase in unsprung wieght My 245/40/18 RT615 on 57f's weighs ~1lb less than stock BBS with 070's
-etc

I am trying to find the pros of this size compared to a 235/40.
The only way I would want to run a 245 would be in a 35, series which is not very commom.

The only "advantage" I give the 235 is that they are the same size as stock...

[AP1toGDRev.G]

"as opposed to the 070 everything is soft. my RT615's are still plenty stiff..."

Well wouldnt a 235 be stiffer than a 245?

So why did you go w/ a 245?

[lackskill]

Originally Posted by AP1toGDRev.G

and they will not rub...

I haven't had any rubbing...

[AP1toGDRev.G]

Ya, I changed the last post, But there is a greater poss. of rubbing w/ a 245...

" not really. I get virtually the same mileage as I did stock." A increae in overall diameter decreases gas mileage, period.

"as opposed to the 070 everything is soft. my RT615's are still plenty stiff..."
Apples and oranges here as we are comparing 18 inch sizes.

"This is just flat incorrect. A 235/40 is very close to the stock height, while a 245/40 is .7" taller than stock. 3% or ~2mph at 60mph difference."
Well first of all we are talking overall diameter not "height." 235/40 > 245/40 when it comes to speedo calibration. You said so yourself if you rad what you post.

"decreases brake performance marginally if at all. tire compound will have a much more profound difference than the slight weight difference. not to mention the larger contact patch of the 245." Marginally or not 235/40 > 245/40 n this cat. also, anyways the larger contact patch is only marginally greater than the 235.

"My 245/40/18 RT615 on 57f's weighs ~1lb less than stock BBS with 070's"
Apples and oranges again, your wheels would be lighter w/ a 235/40.

I win

Sounds like you need a 245/35

[KrazyKarl]

Originally Posted by AP1toGDRev.G

Ya, I changed the last post, But there is a greater poss. of rubbing w/ a 245...

" not really. I get virtually the same mileage as I did stock." A increae in overall diameter decreases gas mileage, period.

"as opposed to the 070 everything is soft. my RT615's are still plenty stiff..."
Apples and oranges here as we are comparing 18 inch sizes.

"This is just flat incorrect. A 235/40 is very close to the stock height, while a 245/40 is .7" taller than stock. 3% or ~2mph at 60mph difference."
Well first of all we are talking overall diameter not "height." 235/40 > 245/40 when it comes to speedo calibration. You said so yourself if you rad what you post.

"decreases brake performance marginally if at all. tire compound will have a much more profound difference than the slight weight difference. not to mention the larger contact patch of the 245." Marginally or not 235/40 > 245/40 n this cat. also, anyways the larger contact patch is only marginally greater than the 235.

"My 245/40/18 RT615 on 57f's weighs ~1lb less than stock BBS with 070's"
Apples and oranges again, your wheels would be lighter w/ a 235/40.

I win

Sounds like you need a 245/35

I'm no expert but here's my take on it:

245/35 would be optimal for a 18x8.5" wheel. this keeps a similar diameter to stock, with a shorter sidewall than stock. Also, the width will be better matched to the wheel (this may depend on the actual width of the tire as 245 is the nominal width and the actual width can vary from tire to tire and brand to brand) since the stock 70's were originally matched to 7.5" wide wheels in '04 and then carried over to the 8" wheels in 05+. These tires seem a bit narrow for the wheels, and this is even more applicable to the average 225 tire, as the 70's are a pretty wide 225. So going from this I'd say 235 is about right for the stock wheels, and since you're going to be going up a half inch in width, you'd want to add about the same in tire width to even things out, so you'd have 245 for the 8.5" wheels.

That being said, 245/35/18 is a much less common size than 245/40 so people use the latter.

anyways I'm probably wasting my breath since teh_clap will prolly come in here and show that everything I've said is wrong haha.

[lackskill]

Originally Posted by AP1toGDRev.G

Ya, I changed the last post, But there is a greater poss. of rubbing w/ a 245...

I will agree, but on stock suspension I have no such problem.

A increae in overall diameter decreases gas mileage, period.

The decrease in my case is less than 10 miles per tank. Not even enough to notice.

Apples and oranges here as we are comparing 18 inch sizes.

my point was that there is always going to be something stiffer. if you want stiff so bad, why dont you run a 235/30/19? That's gotta be stiffer, right? You are talking marginal differences for a street tire, and my guess is that contact patch is > sidewall stiffness for this application.

Well first of all we are talking overall diameter not "height." 235/40 > 245/40 when it comes to speedo calibration. You said so yourself if you rad what you post.

according to this calculator (Tire size calculator) the difference is 3% at the speedo. Which, coincidentally, is ~ the same as the % difference of height from stock to the size in question.

Marginally or not 235/40 > 245/40 n this cat. also, anyways the larger contact patch is only marginally greater than the 235.

Show me. I sure as hell can't find a difference. I can still engage the ABS so leverage hasn't become an issue yet. So if you can still create enough force to overcome your tire's grip then wear rate could be different. Again, I haven't seen any excessive wear that would indicate a problem to me. If I am wrong, show me.

Apples and oranges again, your wheels would be lighter w/ a 235/40.

They would also be lighter with a 215/40/18. What is your point? I chose contact patch over weight and sidewall stiffness. Is it right for you? Maybe not, but that is the choice I and many others have made. Is there any "right" choice? Not really. It's all opinion and speculation. I made the choice I made for me.

I win

Sounds like you need a 245/35

Seriously? Whatever you say man. A 245/35 will increase the inaccuracy of our already off speedo by another 9%. Hmm.. 3% slower reading or 9% faster reading? Like I already said, I made my choice. If you don't like it, what does it matter to you? You asked why people do it, do you really want to know or do you just want to tell people why their opinion is wrong?

[T3h_Clap]

Lots of info here.

first things first.

EDIT: this is all assuming an 18x8.5 wheel.

Rubbing:
235/40/18 will not rub unless your offset is way off.
245/40/18 may rub depending on suspension settings (or your offset is way off).

Speedo/Odo:
This shouldn't be a consideration as the difference is negligible.
If you're looking for a taller 2nd gear for autox then a 245/40 would be beneficial.

Contact Patch/Grip/Braking:
the contact patch is no larger in area between the two. (I'll explain later if need be).
the increase in grip between similar tires is tough to gauge since no one has done a side by side comparison between a wider taller sidewall vs. narrower proper sidewall setup. But in theory the 245 will have better total grip and the 235 will have better turn in.
difference in braking performance is going to be negligible and any loss by the diameter of the 245 will be gained back in the wider contact patch.

Weight:
obviously narrower, shorter sidewall tire will be lighter. No real argument there.

Why do I run a 265/35/18 on a 18x8.5 +45mm?

b/c I can, and these tires will last longer than these wheels will be in my possession and I needed tires that will work for both the 8.5 and the new wheels.

Plus I wanted to make sure a 265 RS2 worked at +45mm.

[AP1toGDRev.G]

Originally Posted by lackskill

I will agree, but on stock suspension I have no such problem.


The decrease in my case is less than 10 miles per tank. Not even enough to notice.


my point was that there is always going to be something stiffer. if you want stiff so bad, why dont you run a 235/30/19? That's gotta be stiffer, right? You are talking marginal differences for a street tire, and my guess is that contact patch is > sidewall stiffness for this application.



according to this calculator (Tire size calculator) the difference is 3% at the speedo. Which, coincidentally, is ~ the same as the % difference of height from stock to the size in question.

Show me. I sure as hell can't find a difference. I can still engage the ABS so leverage hasn't become an issue yet. So if you can still create enough force to overcome your tire's grip then wear rate could be different. Again, I haven't seen any excessive wear that would indicate a problem to me. If I am wrong, show me.




They would also be lighter with a 215/40/18. What is your point? I chose contact patch over weight and sidewall stiffness. Is it right for you? Maybe not, but that is the choice I and many others have made. Is there any "right" choice? Not really. It's all opinion and speculation. I made the choice I made for me.



Seriously? Whatever you say man. A 245/35 will increase the inaccuracy of our already off speedo by another 9%. Hmm.. 3% slower reading or 9% faster reading? Like I already said, I made my choice. If you don't like it, what does it matter to you? You asked why people do it, do you really want to know or do you just want to tell people why their opinion is wrong?

I really hope I did not come off too sarcastic, I am sorry if I did. I am just trying to see if there is something I am missing. Teh 245/35 was kind of a joke.

[AP1toGDRev.G]

Originally Posted by T3h_Clap

Lots of info here.

first things first.

EDIT: this is all assuming an 18x8.5 wheel.

Rubbing:
235/40/18 will not rub unless your offset is way off.
245/40/18 may rub depending on suspension settings (or your offset is way off).

Speedo/Odo:
This shouldn't be a consideration as the difference is negligible.
If you're looking for a taller 2nd gear for autox then a 245/40 would be beneficial.

Contact Patch/Grip/Braking:
the contact patch is no larger in area between the two. (I'll explain later if need be).
the increase in grip between similar tires is tough to gauge since no one has done a side by side comparison between a wider taller sidewall vs. narrower proper sidewall setup. But in theory the 245 will have better total grip and the 235 will have better turn in.
difference in braking performance is going to be negligible and any loss by the diameter of the 245 will be gained back in the wider contact patch.

Weight:
obviously narrower, shorter sidewall tire will be lighter. No real argument there.

Why do I run a 265/35/18 on a 18x8.5 +45mm?

b/c I can, and these tires will last longer than these wheels will be in my possession and I needed tires that will work for both the 8.5 and the new wheels.

Plus I wanted to make sure a 265 RS2 worked at +45mm.

See, I can understand wanting to go w/ a much wider tire, like the 265/35 or 255/35. Now that makes sense, esp. for a track car. But I just feel that the optimal size for a DD w/ 18x8.5 would be the 235/40. And, still believe that the 235/40 is a better tire on your avg. DD stg.II STI than a 245/40.

I also still feel that the "widest" tire i can cram on my wheels is not the best performing, but it is the noisiest...

[T3h_Clap]

I've said this all before.

for 18x(8 or 8.5)s.

235/40/18 grippy summer tire is the ideal setup for a street driven STi.

[lackskill]

Originally Posted by AP1toGDRev.G

I really hope I did not come off too sarcastic, I am sorry if I did. I am just trying to see if there is something I am missing. Teh 245/35 was kind of a joke.

I was a little frustrated by it, but nothing I won't get over. No harm no foul.

I hear what you are saying, I was just giving you my reasons for making my decsision.

My wheels are gramLight 57F's with RT-615's.