Guise - I need some help with tires

[SSSnail]

It's a two parts question, and my let's just say my tires are 225/40/19 fronts and 255/35/19 rears.

1. What's the highest height ratio I can go without getting out of speedometer and safety specs?

2. If I decide to go 255/35/19 or 255/40/19 all around, aside from the increased oversteer, anything else do I need to worry about?

Thanks!





Closed at OP's request.


esquared
Anandtech Forum Director

 

[jlee]

You'll want to make sure wider tires will clear your body/suspension.

http://miata.net/garage/tirecalc.html

Can help you with ratios.

 

[NutBucket]

I agree with jlee. Don't forget about wheel offset either. If you really want to save a few bucks maintain the same overall rear diameter and run 225 at all 4 corners.

 

[SSSnail]

You'll want to make sure wider tires will clear your body/suspension.

http://miata.net/garage/tirecalc.html

Can help you with ratios.

So I plugged in some numbers, are the percentage differences are the speed differences? I'm not a math wiz.

How much impact do you think the .5" height difference will make on handling between 255/35 and 255/40?

Nutbucket, what potential setback should I expect if I run 225 all around? This is for a xDrive car, with 20/80 default rear bias.

 

[NutBucket]

I have no idea. Offset is relative to wheel width so it doesn't do much good to compare the wheels you have now since they're different widths. If anything, bolt your front wheels on the back and see what it looks like. If the everything looks good then just get two front wheels for the back and run 225/40 at all 4 corners.

This sounds very similar to those that buy luxury cars and then complain about the extra cost of premium fuel.....

 

[SSSnail]

Huh? Where did you get the cost thing from?? Is that how you think? Nowhere in this thread anyone mentioned anything about cost, except from you.

I was asking about technical and safety differences, because you know, 255 all around is more expensive than 225s? Just saying.

And of course, I'm not going to get wheels that don't have the correct offset for the car, any idiots would know at least that.

 

[jlee]

Huh? Where did you get the cost thing from?? Is that how you think? Nowhere in this thread anyone mentioned anything about cost, except from you.

I was asking about technical and safety differences, because you know, 255 all around is more expensive than 225s? Just saying.

And of course, I'm not going to get wheels that don't have the correct offset for the car, any idiots would know at least that.

You should be able to get more life out of a square setup than offset widths because you will be able to rotate tires.

 

[SSSnail]

You should be able to get more life out of a square setup than offset widths because you will be able to rotate tires.

Yeah, this will be the second car with staggered setup, as I don't rotate tires on the other. My other car is a straight FR layout, so staggered was a good setup. This one has xDrive, albeit it's rear bias, but it's a bit more complicated so I don't know what the impact would be if I change the tires configuration.

I guess I'd just keep the staggered setup, but since these are RFT, I kinda want to give them a bit more sidewall hence the increase ratio question. Just want to know if anyone has experience with these setups, and if there are setbacks that I should know about. That's all.

 

[NutBucket]

Wanting to switch to a square setup seems like something that would mainly be done to save money. If there was a performance benefit then it would have come that way from the factory IMHO. Again, just my opinion. I guess I don't worry much about tire wear. I just replaced the tires on our WRX a couple months ago because they were getting old. Still had about 4/32" I would say. Went with summer tires this time instead of all-seasons

 

[SSSnail]

Yeah, but context is everything .

In this case, 255s would be inherently more expensive than 225. The CINTURATO P7 AS run-flats are almost 100 bucks more per tire in 255 than its 225 iteration. And no, I can't afford summer, because I don't have space for a spare.

The manufacturers setup staggered because it makes their cars "safer" to drive with a FR layout. Granted I'm not going to hit that performance limit in daily driving to be worrying about over-steer or under-steer much, but it's nice to know the effects so I won't be surprised when I do have the need (or before I spend the money).

Anyways, I have some more googling to do then, as no one seems to know.

 

[NutBucket]

Do you often drive places where you can't be stuck without a spare/runflats? If you're not road tripping and/or live in a rural area I would really think about just buying non-RFT when the OEMs are worn out.

Anyway, I agree that most people would be hard pressed to notice a difference in performance going from a staggered to square setup.

 

[SSSnail]

No, we're in SoCal; although catastrophic failure of tires are very rare nowadays, but I like to have that added layer of safety when toting my wife and kid around. The wife is also the reason for the wider square setup, she likes the wider tires look...

 

[jlee]

It's going to come down to the specific car - i.e. will additional tire width cause the tire to hit the upper control arm? Will you be rubbing fender liners at full lock?

You could swap wheels, rear to front, and (very carefully) see if you have any clearance problems. That'd probably be the easiest way to be sure.

 

[NutBucket]

Then it seems like the best solution is pay to play

 

[SSSnail]

LOL, that has NOTHING to do with what was asked, again.

 

[tortillasoup]

It's a two parts question, and my let's just say my tires are 225/40/19 fronts and 255/35/19 rears.

1. What's the highest height ratio I can go without getting out of speedometer and safety specs?

2. If I decide to go 255/35/19 or 255/40/19 all around, aside from the increased oversteer, anything else do I need to worry about?

Thanks!

With a tire size of 255/35, the "35" is the sidewall height and it's a ratio in that it means 35 % of 255 which is 89.25mm. If you go with a 255/40, then you have a sidewall height of 102mm. Any change to the height ratio will affect speedometer specifications unless you change the tire width so that the sidewall height stays the same and that assumes no change in rim size.

 

[JEDIYoda]

LOL, that has NOTHING to do with what was asked, again.

yeah but I you go back and read your posts it seems to have a lot to do withy it...

 

[NutBucket]

Thank you.

 

[SSSnail]

yeah but I you go back and read your posts it seems to have a lot to do withy it...

Which part? Maybe my English is not coming through. Just curious. Of course cost is always a consideration, since the wife likes the look and that's it. Anyways, I'm not a baller like you ATOT millionaires with my meager salary, so I'll have to be careful with what I spend my money on.

It started out with me asking about if there are any negative effects if I go to a larger size tires in the front, and maybe higher height ratio. I really have no idea how you ballers figured that was about cost... Amazing.

Then, I have a guy that came in and basically tells me about height ratios, which if he bothers to read the OP carefully, he'd know that the conversation is beyond what he just posted.

I'm starting to think that the problem is somewhere else...

JLee, you're the only one that actually helped. Thanks. I'm going to ask mods to lock this thread as it's getting pretty stupid in here.

 

[NutBucket]

And it doesn't seem like you tried our advice: bolt the rear wheels up front and see if it rubs. If not you're golden. If so, it is likely you'll have to downsize the rears to achieve a square setup.

I'll refrain from any other monetary comments.

 

[SSSnail]

No, the problem with this is your mentality of insisting that I WANT to go to square setup, when my question was simply "IF I INCREASED THE FRONT TIRE SIZE". Is that cleared enough for you? Do you have problems with reading comprehensions?

As for monetary comment, you'd have to be a flipping idiot to think that by purchasing a set of new wheels, and larger tires, is somehow saving money and it's purely because the wife wants a different look (if there are no negative effects). How many sets of tires do you have to rotate to offset that cost?

How about just sticking to the questions in the OP, and if you don't know, then don't comment.

Edit: And NO, you don't get credit for what JLee posted, thanks but just no so don't start with that "our suggestions" shit.

 

[tortillasoup]

Then, I have a guy that came in and basically tells me about height ratios, which if he bothers to read the OP carefully, he'd know that the conversation is beyond what he just posted.

I'm starting to think that the problem is somewhere else...

JLee, you're the only one that actually helped. Thanks. I'm going to ask mods to lock this thread as it's getting pretty stupid in here.

No, the problem with this is your mentality of insisting that I WANT to go to square setup, when my question was simply "IF I INCREASED THE FRONT TIRE SIZE". Is that cleared enough for you? Do you have problems with reading comprehensions?

As for monetary comment, you'd have to be a flipping idiot to think that by purchasing a set of new wheels, and larger tires, is somehow saving money and it's purely because the wife wants a different look (if there are no negative effects). How many sets of tires do you have to rotate to offset that cost?

How about just sticking to the questions in the OP, and if you don't know, then don't comment.

Edit: And NO, you don't get credit for what JLee posted, thanks but just no so don't start with that "our suggestions" shit.

I really don't care. You sound very scattered brained and have no idea what you want or what you're talking about. I merely responded to your OP. I just do not care that much and frankly I don't think you can be helped.



I'll try it again. In one sentence, explain what you want. I thought your OP was pretty clear but I guess not.

 

[NutBucket]

I have a suggestion that's actually logical; Browse a forum for said car and see what kind of wheel/tire combos people are running.

 

[Wuzup101]

I have a suggestion that's actually logical; Browse a forum for said car and see what kind of wheel/tire combos people are running.

This.

You'll get way better specific advise at a car model specific forum. I know for both my vehicles (evo x / corvette) I can find hundreds of different posts about rim / tire sizing, offsets, etc...

What sort of car is this going on? bimmer?

225/40/19 and 255/35/19 are almost identical in overall diameter. You shouldn't have any issues swapping the 255's on the front (besides a bit more push... nothing a bit more rsb can't fix). As at least one poster above said... you will have to look at:

1. How much clearance do you have from the inside of the rim to the suspension

2. How much clearance do you have from the outside of the tire to the fender

3. How much clearance do you have from the inside of the tire to the fender well / lining (these are often easy to modify)

4. If you have large brakes, you'll have to ensure that your new wheels will clear the calipers. Note that not all rims of a given size are created equal (spoke design and offset are important).

 

[SSSnail]

I really don't care. You sound very scattered brained and have no idea what you want or what you're talking about. I merely responded to your OP. I just do not care that much and frankly I don't think you can be helped.



I'll try it again. In one sentence, explain what you want. I thought your OP was pretty clear but I guess not.

Do you have a problem with English? Here, let me quote my OP again.

1. What's the highest height ratio I can go without getting out of speedometer and safety specs?

This right here, tells you that I know about the ratio of tire width to its height (no need for you to go all Wiki on me). I'm just asking what's the safety limit (with regards to the original tires) and without getting the speedo all out of whack, i.e. a reasonable limit.

2. If I decide to go 255/35/19 or 255/40/19 all around, aside from the increased oversteer, anything else do I need to worry about?

This here tells you that I know enough about the effects of wider tires in front. And merely asking if there's anything else I should worry about, which JLee (again, thank you - you're the only smart guy that posted answers in this thread so far) addressed.

Sometimes, people think they're too smart for their own goods.

I have a suggestion that's actually logical; Browse a forum for said car and see what kind of wheel/tire combos people are running.

Now, this is actually constructive and reasonable. But I figure I'll try this forum first as there are a lot of knowledgeable folks here.

See? It's not that difficult.