Decision to make on tire size

[eliwwjd]

Im about to be done with my contis extreme contact sport tires and i need to change tires soon. At the moment im on oem size 225/40 R18 but was considering on a tire that would fill a little bit more the area without the need to lower springs and also get better acceleration, grip and traction. My friend recommended me 235/40, get a little wider and at the same time a slight higher sidewall. The other size i though about was 225/45 but not sure if this size would look good. Im so undecided here!

[Bertospeed3]

Tire size wont reduce wheel gap much. You'd have to modify the suspension.

[ThorOtheBIG]

It's simple. Do the math.

225/40 = 5.625 Stock tire sidewall height

235/40 = 5.875 Friend's recommendation

225/45 = 5 The tires that you are looking at

So, it seems like your friend recommended tires that are taller than stock, which means it would "fill" the gap more. The tires you are looking at are very short, meaning your tires will appear smaller (more gap). I'd listen to your friend.

Also, Bertospeed3 is right.

Personally, I put some slightly wider and taller tires on my Mazda5. It helped grip, but reduced MPG by, idk, 5%?

[Oshiguru]

Originally Posted by ThorOtheBIG It's simple. Do the math. 225/40 = 5.625 Stock tire sidewall height 235/40 = 5.875 Friend's recommendation 225/45 = 5 The tires that you are looking at So, it seems like your friend recommended tires that are taller than stock, which means it would "fill" the gap more. The tires you are looking at are very short, meaning your tires will appear smaller (more gap). I'd listen to your friend. Also, Bertospeed3 is right. Personally, I put some slightly wider and taller tires on my Mazda5. It helped grip, but reduced MPG by, idk, 5%?

You don't divide. The second number is the aspect ratio which is a percentage of the first number that determines the sidewall height. Think of tire 1's sidewall as 40% of 225, tire 2 is 40% of 235, and tire 3 is 45% of 225. The 225/45 is the tallest of all the three.

https://www.willtheyfit.com/index.ph...7-5&offset2=52

https://www.willtheyfit.com/index.ph...7-5&offset2=52

@OP
It also depends on what wheels you have and what tire you go with. Some tires run wider than others. I went from 225/40 on a 18x9 to a 245/40 and the wheel gap difference is minimal. It did "fill the gap" because the old tires were stretched and the new ones are not.

https://i.imgur.com/ejjxfgK.jpg 225 Michelin PSS
https://i.imgur.com/5pjgFZE.jpg 245 Michelin PS4S
Same wheels

[ThorOtheBIG]

Oh boy. That's right. HAHA! What an asshole *points to self*

More coffee for me.

Let's try this again.

225 * .4 = 90mm Stock tire sidewall height

235 * .4 = 94mm Friend's recommendation

225 * .45 = 101.25mm The tires that you are looking at

See if you can do a 235/45.

235 * .45 = 105.75mm

[Pu Manchu]

Originally Posted by eliwwjd was considering on a tire that would fill a little bit more the area without the need to lower springs and also get better acceleration, grip and traction.

are you sure a taller tire will help these things?

[Jeff23spl]

a taller tire to fill the gap may also rub on the inner fender front. unless you do it by the ratio (45 instead of 40) but at some response loss. Your speedo will also be underrated and gears will get taller to make the car accelerate slower....

Probably not the best option ever....

[eliwwjd]

So you mean 225/45 not the right choice? go instead with 235/40?
My friend has the 235/40 size on his car and i asked him if he noticed any changes in gas, road noise and acceleration differences and he said it felt same as oem size. This size is not suppose to run on fender.

[MSMS3]

It’s far more important that you get the best tire design and compound than obsess over trying to go wider and have less support on your rims or taller and lose gearing and induce speedometer error.

Get the best stock size tire you can afford: Extreme Performance rated summer tire or UHP all season.

My choice for a summer tire was the Extreme Performance rated Yokohama Advan Neova AD-08R. Very close to race rubber but with long life and very good wet traction as well. Michelin Pilot Sport 4S is the clear choice in the Max Performance category which gives up a little dry grip for a little better wet performance.

My UHP all season choice would be Michelin Pilot Sport A/S 3+, or the Conti DWS 06 you may be running now.

[Oshiguru]

Originally Posted by eliwwjd So you mean 225/45 not the right choice? go instead with 235/40? My friend has the 235/40 size on his car and i asked him if he noticed any changes in gas, road noise and acceleration differences and he said it felt same as oem size. This size is not suppose to run on fender.

I'm guessing you're on stock wheels.

IMO. stay with 225/40 but get a stickier compound. Maybe one of the ones mentioned above. I generally noticed the stickier my tires, the worse my mileage and road noise got; but thats a small sacrifice for grip

[Carskick]

On stock Gen 2 wheels, 225 is a good width. Go too wide and you can have rollover. 235 max, IMHO. If want more lateral grip, go wider wheels. Otherwise, stay stock size and stickier compound will be the easiest fix. Stickier compounds tend to get worse MPG as generally have a higher rolling resistance.

The Contintental ExtremeContact Sports are pretty sticky. Not quite R rubber, but on par with Michelin PSS. I run the same tires as 245/40/18, but they're on 8.5" wide wheels.

As others mentioned, the larger the diameter of the tire, the more it will create speedo error and widen gear ratios. My Gen 1 speedo was always about 2MPH over reality, with 245/40, the slightly larger sized made it basically dead on.

[eliwwjd]

Thanks to all those who have kindly shared their opinions and suggestions.
By any chance is there any member here who has 235/40 R18 tires mounted on stock rims and oem suspension that can kindly share some pictures? Thanks in advance for your help!

[Bertospeed3]

Originally Posted by eliwwjd any member here who has 235/40 R18 tires mounted on stock rims and oem suspension

My old stock setup. Only difference is I was running 25mm spacers but that should not make a difference in what you're looking for.

[eliwwjd]

Originally Posted by Bertospeed3 My old stock setup. Only difference is I was running 25mm spacers but that should not make a difference in what you're looking for.

Dam! it looks really good! Thanks for kindly sharing. How did it perform in comparison with 225/40?

[eliwwjd]

Originally Posted by Bertospeed3 My old stock setup. Only difference is I was running 25mm spacers but that should not make a difference in what you're looking for.

I sent you a PM but not sure if you got it. Let me know if you did. Thanks guy

[eliwwjd]

Once again thanks to all the great members here who have kindly shared your thoughts and helped me decided. Here is the thing, Continental is giving me a 60 days trial so i can test the tires. The manager told me to try them(do not track them) if i don't like them, i can return them. I'm going to try 235/40 to see how car behaves, if not i can go back to 225/40.
They also gave me a warranty wear out credit of almost $300 because my tires lasted 15K miles so shipped to P.R. we are talking about $600 for all 4 and thats not bad, these tires here cost over $200 a piece.
Some of you mentioned here "response loss" but theorically a wider tire is suppose to give you better acceleration and grip right? so that been said anybody here with stock rims that have gone to 235/40 experienced any response loss? because from what some people have told me is they felt as oem and didn't noticed any response loss and what continental told me is that the difference between 225/40 vs. 235/40 is very minimal practically un-noticable but i always like to see from users what has been the real life experience

[MSMS3]

Braking might be a tiny bit shorter 235mm vs 225mm same tire, otherwise.

Acceleration might be a tiny bit slower with the same 40 aspect ratio profile, because it will be a little taller, effectively making gearing a little bit taller. Speedo will be off a little.

Unless rims are widened, slightly wider tires otherwise identical may handle worse, as they tend to roll over easier and weight more.

[eliwwjd]

Originally Posted by MSMS3 Braking might be a tiny bit shorter 235mm vs 225mm same tire, otherwise. Acceleration might be a tiny bit slower with the same 40 aspect ratio profile, because it will be a little taller, effectively making gearing a little bit taller. Speedo will be off a little. Unless rims are widened, slightly wider tires otherwise identical may handle worse, as they tend to roll over easier and weight more.

Well acceleration is suppose to improve technically because you get better grip with a wider tire, think about it why do drag strip cars have installed wider tires.
Handling does improve according to a few who haved made the change to 235's, in a sense they are still a low profile tire so no roll over takes place, at least according to the few that have made the change. Tire weight is very relative because for instance conti extreme contact weight 21 pounds which is less weight then the majority of the tires on the market. I used an oem size tire made by bridgestone which weight 25 pounds.Trust me that is one of the things i look into, weight. This tire is the one of the least that weights, so more weight isn't an issue for me considering the tire ill be using. Will see when i get the tires what happens. Height adjustment from one to the other is .2 to .3 inches, thats barely nothing

[Carskick]

Taller gears will give worse acceleration, assuming you have traction. Will 235 give you more grip than 225 on stock wheel? Maybe. Depends on which tire. But a wider wheel is needed to fully take advantage of it. A lot of variables. As others said, compound will likely matter most to determine traction/grip.

[MSMS3]

Originally Posted by eliwwjd Well acceleration is suppose to improve technically because you get better grip with a wider tire, think about it why do drag strip cars have installed wider tires. Handling does improve according to a few who haved made the change to 235's, in a sense they are still a low profile tire so no roll over takes place, at least according to the few that have made the change. Tire weight is very relative because for instance conti extreme contact weight 21 pounds which is less weight then the majority of the tires on the market. I used an oem size tire made by bridgestone which weight 25 pounds.Trust me that is one of the things i look into, weight. This tire is the one of the least that weights, so more weight isn't an issue for me considering the tire ill be using. Will see when i get the tires what happens. Height adjustment from one to the other is .2 to .3 inches, thats barely nothing

Your preconceived bias is showing. With respect, you are minimizing the very real negatives and maximizing trivial, if existent, positives.

Taller tires is taller gearing, which is slower acceleration. Fact. Period.

Wider tires does not mean better handling, especially on stock rims. Weight will go up. That is more unsparing weight, the worst kind. The outside and inside edges will have less support and will tend to roll in corners, causing the opposite side to lift away from the pavement if not supported by a similarly wider rim.

Wider may not actually put more rubber in contact with the road. These are not drag slicks. Actually taller will put more rubber in contact than wider. The contact patch is small, but it goes all the way around as the tire rotates, that is why drag tires tend to be tall, but the gears are shortened to compensate for this, which you are not.

There is extremely robust research on effect of height and width on contact patch and traction.

You get far more grip from softer tread compound and less voids in the treads than from increasing width. If you want more grip go with dedicated Extreme Performance summer tires in stock width to match your rims.

It seems you are seeking approval of an already made decision regardless of the facts. That is called confirmation bias. Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms one's preexisting beliefs or hypotheses. It is a type of cognitive bias and a systematic error of inductive reasoning. In short, because you want it to be true, therefore it is true.

For what it is worth, Car and Driver, not too long ago, published an article that showed that wider, heavier tires, even if the same height, often produce slower lap times unless rims are widened too, as the wider tires roll laterally on the rims in cornering.

Look, if you want 10mm wider tires that are also taller because they look good or may fill out your wheel wells a bit more (the original purpose of your post), go for it. It will make you happy. Just don’t expect us to validate a performance gain.

[Jeff23spl]

You also need to separate handling feel VS faster lap time....
smaller sidewall gives more feedback into the steering wheel but it isn't giving the best traction contact with the road. Manufacturer don't increase wheel size for handling but to fit larger brakes....