tires..

[Mid_Life_Crisis]

You do not want to put anything larger than a 225 width tire on the stock rims. And I would highly recommend not getting anything taller than a 40 sidewall on any tires larger than 225 if you want the thing to handle at all. To keep your overall diameter as close to stock while increasing the contact patch (keeping your speedometer correct) stick with a 225/40/r18.

If you swap out rims at the same time, 235/40 is the closest thing to the diameter of the stock 215/45. It also adds enough additional meat to make it worth the new rims.

 

[freebird_78]

Anyone read this month's Car & Driver (very last page) where someone wrote in dispelling the myth about wider tires having a larger contact patch. Contact patch is a function of vehicle weight vs tire pressure. Only the shape of contact patch will change with wider tires.

EDIT: That being said, I went with Nitto NT555s in 225/40 on a 7.5" rim.

 

[dkswim]

i need to get me a set of new tires this summer

 

[mazdaspeed32007]

Anyone read this month's Car & Driver (very last page) where someone wrote in dispelling the myth about wider tires having a larger contact patch. Contact patch is a function of vehicle weight vs tire pressure. Only the shape of contact patch will change with wider tires.

EDIT: That being said, I went with Nitto NT555s in 225/40 on a 7.5" rim.

I might have to read this article. I cant see how someone with a 245 isnt putting down more rubber than someone with a 215. I can understand if the weight of the car cant push the tire down if you went to large, but I only think this might have an effect if your cars weight and the size of the tire cant relate mathematically or something. aaaand with that being said I found out I can get falken 452's for 145 a piece with free installation, alignment, balance, blah blah blah. I don't think i can complain about that. I might have to take a trip out there tomorrow afternoon to purchase them. what do yall think of the deal? deal or no deal? lol. actually im not going to lie....i might wait until i get my exhaust on in two weeks. besides that...yey?

 

[freebird_78]

I might have to read this article. I cant see how someone with a 245 isnt putting down more rubber than someone with a 215. I can understand if the weight of the car cant push the tire down if you went to large, but I only think this might have an effect if your cars weight and the size of the tire cant relate mathematically or something. aaaand with that being said I found out I can get falken 452's for 145 a piece with free installation, alignment, balance, blah blah blah. I don't think i can complain about that. I might have to take a trip out there tomorrow afternoon to purchase them. what do yall think of the deal? deal or no deal? lol. actually im not going to lie....i might wait until i get my exhaust on in two weeks. besides that...yey?

It just makes sense. If the weight of the vehicle remains constant, and the pressure of the tire remains constant, the total contact patch area can't change. Works the other way too. If the vehicle weight is constant, tire size constant, and pressure drops, your contact patch will increase. Pressure and pressure constant and vehicle weight increases (or in the case of downforce), contact patch increases.

 

[ccann26]

It looks pretty cool but your probably going to be spinning your tires a bit not to mention the curbing of the rims will be much much easier .(yupnope)

 

[Mid_Life_Crisis]

It just makes sense. If the weight of the vehicle remains constant, and the pressure of the tire remains constant, the total contact patch area can't change. Works the other way too. If the vehicle weight is constant, tire size constant, and pressure drops, your contact patch will increase. Pressure and pressure constant and vehicle weight increases (or in the case of downforce), contact patch increases.

I think you're missing something here. By your logic, a 4 inch wide tire would have the same contact patch as an 8 inch wide tire. I haven't seen the article, but I will bet money they were talking about the depth of the patch, not the width. Remember that the patch is more or less rectangular. The depth of it front to back will not vary for the very reasons you state, but the width of the patch has to change to reflect the wider tread area. A properly adjusted tire will put the entire (flat) tread width to the ground. More tread equals wider contact patch. Because the front to back is defined by an arc (round tire), the pressure of the weight of the car pushing down against the air in the tire will determine that dimension, so it should be pretty much the same for any size properly adjusted tire on the same car.

 

[freebird_78]

I think you're missing something here. By your logic, a 4 inch wide tire would have the same contact patch as an 8 inch wide tire. I haven't seen the article, but I will bet money they were talking about the depth of the patch, not the width. Remember that the patch is more or less rectangular. The depth of it front to back will not vary for the very reasons you state, but the width of the patch has to change to reflect the wider tread area. A properly adjusted tire will put the entire (flat) tread width to the ground. More tread equals wider contact patch. Because the front to back is defined by an arc (round tire), the pressure of the weight of the car pushing down against the air in the tire will determine that dimension, so it should be pretty much the same for any size properly adjusted tire on the same car.

Area = length X width

Area = weight / pressure

Therefore:

Length X Width = Weight / Pressure

And if Weight and Pressure are consant, and if width is increased, length must decrease to keep area constant (inversely proportional).

http://forum.miata.net/vb/showthread.php?t=38946&page=1&highlight=Wider+Tires+Provide+Traction

 

[mazdaspeed32007]

Area = length X width

Area = weight / pressure

Therefore:

Length X Width = Weight / Pressure

And if Weight and Pressure are consant, and if width is increased, length must decrease to keep area constant (inversely proportional).

http://forum.miata.net/vb/showthread.php?t=38946&page=1&highlight=Wider+Tires+Provide+Traction"

i think i understand. so if the tires become wider, the contact patch size is negated by the length if all else stays constant. i think thats whats being said.

either that or the width is increased but the length of the contact patch stays the same.

 

[freebird_78]

i think i understand. so if the tires become wider, the contact patch size is negated by the length if all else stays constant. i think thats whats being said.

either that or the width is increased but the length of the contact patch stays the same.

The first one is correct.

 

[Mid_Life_Crisis]

I followed the link to the other thread and the guy is being misquoted. He did not say that increasing tire width does not help. He did say that as you increase the width, you will eventually get to a point where the additional width provides no effective increase in traction. The old "Law of diminishing returns" coming into play.
Does anyone have a link to the Car & Driver article? I would love to see what they had to say.

 

[mazdaspeed32007]

yea thats what i was saying originally. once you reach a point mathematically where the weight of the car can no longer meet the tires ability to keep increasing the contact patch then your just putting on a bigger tire for nothing.

 

[freebird_78]

Where is the misquote?

Strait from the link:
"CHANGING TO A WIDER TIRE WON'T INCREASE THE CONTACT PATCH; IT WILL ONLY CHANGE THE SHAPE OF THE CONTACT PATCH"

Its simple math (see my previous post for equations). Better yet, READ the link.

 

[mazdaspeed32007]

i read about 10 posts to that thread and this is what i feel is the best explaination to that article. (supposedly outdated)

"The way I understand it (and how it was basically explained by one of my ME prof's, that is if I remember it correctly) is that when the tire deflects in response to a load (lateral, acceleration, etc) that the wider/bigger tire has more tire to deflect to before traction is lost. As you're basically spreading the forces out over a larger piece of rubber, each individual piece has to do less work to provide the same amount of grip and therefore it would take more force to break the tires loose."

I believe that at a certain point between weight/tire size you will meet an end where you will recieve no more traction due to the size of the contact patch. The amount of weight each tire needs to deflect will be different. It will go down as the tire gets bigger until you reach a point where the contact patch wont change. liek if you have a tire thats 215 that deflects 600 lbs and has a contact patch of 9.5 inches. a 225 will deflect the same amount of weight but over a larger surface giving the contact patch 10 inches. but lets say you put on a 235 and it has a contact patch of 10 inches, well thats where you found the cars maximum tire grip. once you hit a point where the weight can no longer effect the tires contact patch, youve reached its maximum weight/contact. does that make sense to anyone? im usually no good at explaining things.

 

[Swerny]

So, is anyone here running 225-40-18 rubber on the OEM MS3 rims?

I'm looking to pick up a set of the rims for the 3 Sport I'll be getting soon and want to run that size (closest to the OEM size of 205-50-17).

I have read on several sites that a minimum 7.5 inch wide wheel is required.

Thanks

 

[squabbin]

I personally am not yet, however I have just purchased a set of 225/40/18 Pirelli Winter 210 SnowSport's that i'll be using during the colder snowy months here in NJ and from everything i've read 225/40/18 should be no problem whatsoever on the stock MS3 rims.

 

[mazdaspeed32007]

i just bought a new set of rims 7.5 and bought a 225-40-18 falken 452. sweet ass tire. def worth it. it will fit on the stock rim and i highly suggest it.

 

[ericrapp]

So, is anyone here running 225-40-18 rubber on the OEM MS3 rims?

I'm looking to pick up a set of the rims for the 3 Sport I'll be getting soon and want to run that size (closest to the OEM size of 205-50-17).

I have read on several sites that a minimum 7.5 inch wide wheel is required.

Thanks

You probably know that the Mazdaspeed 3 has 215/45/18 on the 7" wheel. The 225 is a bit much. I am running Nitto- 555 at 225/40/18 on an 18 x 8 wheel, if you want traction and are wiiling to sacrifice longevity this might work.

 

[ericrapp]

Nice

i just bought a new set of rims 7.5 and bought a 225-40-18 falken 452. sweet ass tire. def worth it. it will fit on the stock rim and i highly suggest it.

Excellent tire and good fitment. Bring on the hairpin turns!

 

[SSMS3]

Diameter should also be considered since it changes your effective gear ratio and speedo/odo. Stock tires are 25.7"