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Re: PERFECT!

HawaiianTime said:
But seriously, on the MPG issue - if you put tires with more rolling resistance (usually = more traction) you will lower you gas mileage. Aggressive all terrain, mud/snow, and some high performance tires will do this. Bias Ply tires have more rolling resistance than radials as well. I am talking from real life experience, not info on a website.
But seriously, basic laws of physics apply here.

If you have more friction you are going to need more force to move an object. If you try to push a box accross the cement, it takes more effort than pushing it across ice. Why? Friction, cement is rough and there is more friction than on the ice.

The same is true for tires. The more friction you have, the better the tire will grip, but that also means that you will need to apply more force to move, and that affects your gas mileage.
 

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Discussion Starter #22
Re: Re: PERFECT!

gmc74 said:


But seriously, basic laws of physics apply here.

If you have more friction you are going to need more force to move an object. If you try to push a box accross the cement, it takes more effort than pushing it across ice. Why? Friction, cement is rough and there is more friction than on the ice.

The same is true for tires. The more friction you have, the better the tire will grip, but that also means that you will need to apply more force to move, and that affects your gas mileage.
Exactly. And the force required to roll a tire across cement is more dependent on the tread pattern's rolling resistance than width (unless the tire is substantially wider - like 25% wider than stock).

The laws of mechanics and mathematics also make a taller tire require less engine RPM's to cover the same distance / maintain the same speed (just like Overdrive does) therefore saving gas.
 

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So, what's the widest tire that can fit on 07 MDX? I want to go 275 but do not want the tire to be sticking out or rubbing.
 

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Re: Re: Re: PERFECT!

HawaiianTime said:


Exactly. And the force required to roll a tire across cement is more dependent on the tread pattern's rolling resistance than width (unless the tire is substantially wider - like 25% wider than stock).

The laws of mechanics and mathematics also make a taller tire require less engine RPM's to cover the same distance / maintain the same speed (just like Overdrive does) therefore saving gas.
Tall and thin is fine, wide is the issue. The amount of tread touching the pavement is a direct correlation to the friction that is caused, so regardless of how much wider a tire is, if it is wider, the mpg will go down.

There is a reason that cars trying to break the land speed record, or solar powered cars use discs instead of real wheels (at least on the front wheels), they have very little friction.
 

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Discussion Starter #25
Taller Wider

I have direct experience on 2 - 4x4's getting better MPG with taller & wider tires. So long as the tread pattern is no more aggressive than stock, you will not hurt your MPG.

However, a lower profile tire like a 30 series or less WILL lower your MPG NOT because the tire is wider but because the overall tire diameter is smaller thus requiring more tire revolutions per mile (like driving in 3rd gear on the freeway). Your engine RPM's will be higher at any given speed as well with lower profile tires. The only way around this is by also increasing the rim diameter when going to a 30 or 20 series tire. But beware, shorter sidewalls = harsher ride and easy tire & rim damage on potholes, etc.

If you look at detailed tire specs on the tire manufacturers' web site it will show "revs per mile" for each tire size. To preserve MPG you need equal to, or less revs per mile than stock size.

So what is the biggest size that will fit???

Aloha
 

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m500 said:
So, what's the widest tire that can fit on 07 MDX? I want to go 275 but do not want the tire to be sticking out or rubbing.
If you go to Tirerack.com and plug in your vehicle, it will show you that a 275x45x19 is the recommended OEM upgrade for the 07' MDX. I have this upgrade and it is just fine. It does not rub and it does not stick out any further than the original tires. If you would like to go with something larger than 19" wheel, wider than 275, and a lower sidewall than 45, you are on your own. Meaning, you may end up affecting the various safety control systems in the car (ABS, stability control etc.), possibly in a bad way. Besides, the 275's are about as wide as you would want to go anyway. They make the MDX look mean and meaty from the front and rear of the vehicle. Very nice!!:)
 

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Discussion Starter #27
Seang, any photos of your rims / tires on your MDX?

Thanks, HT
 

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seang said:


If you go to Tirerack.com and plug in your vehicle, it will show you that a 275x45x19 is the recommended OEM upgrade for the 07' MDX. I have this upgrade and it is just fine. It does not rub and it does not stick out any further than the original tires. If you would like to go with something larger than 19" wheel, wider than 275, and a lower sidewall than 45, you are on your own. Meaning, you may end up affecting the various safety control systems in the car (ABS, stability control etc.), possibly in a bad way. Besides, the 275's are about as wide as you would want to go anyway. They make the MDX look mean and meaty from the front and rear of the vehicle. Very nice!!:)
Thanks Seang.

I wonder if my Stock 18" will fit 275 tire on it or not??? Anyone tried.?
 

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You can get bigger and wider tires and still get better fuel economy, but you have to get significantly lighter wheels to do it.

And I've already proven it on my Civic (my other vehicle).

OEM tires were ho-hum average 205/55 16", but the OEM wheels weigh ~25 pounds.

I went with an 225x18" high performance (Z rated) Sumitomo tire and have suffered no fuel economy loss at all, but the trick was getting 20 pound wheels to offset the extra grippiness of the tires.

The biggest problem most people have when upsizing is that they pick wheels which are also heavier, which will kill your fuel economy because adding weight to the rotating mass of your wheel+tire combo is the absolute worst place you can add weight.
 

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How Big Can You Go On Stock 18" Rims?

In reading all of the responses on this thread, the one thing lacking is an actual answer to the question. What is the biggest, widest tire that will fit on a stock 18" rim? I'd be interested in seeing an answer if anyone has it.
 

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In reading all of the responses on this thread, the one thing lacking is an actual answer to the question. What is the biggest, widest tire that will fit on a stock 18" rim? I'd be interested in seeing an answer if anyone has it.

I concur
 

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I just installed winter tires and upsized diameter by 5.1% - 265/60/R18 = I could not get anyone to tell me I could or could not do this so I took a stab in the dark - they look great and no issue of rubbing, even at extreme turning angle - check out the uploaded photos after and before
 

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Max tire size

In reading all of the responses on this thread, the one thing lacking is an actual answer to the question. What is the biggest, widest tire that will fit on a stock 18" rim? I'd be interested in seeing an answer if anyone has it.
Hey Sabooba, I share your frustration - lots of people stand ready to state the obvious, but few offer valuable facts. I am a mechanical engineer and I made a considerable effort to find what the technical limits were for increasing wheel size - for rubbing, SH Awd performance, and handling. All I ever get is blanket statements of no more than 3% increase which covers all vehicles - which is crap. So that leave me with no choice but trial and error. Because I do want to fill my wheel wells to improve the look - of the higher end cross over models out there, MDX has the wimpiest looking tire size, and I am determined to fix this.

So first trial is winter tires - see earlier post with pictures (more available if interested). I increased the diameter by 5.1% (1.5"). Next is summer tires this spring - I plan to move to 6-7% on 19 or 20" rims - I will post my experience - I encourage others to do the same.

Cheers

Eric
 

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^^^ That's the worst advice I've read on these forums.

Using larger diameter tires have no advantages and a whole lot of downsides, including slower acceleration, poorer handling, making your speedometer and odometer inaccurate, rubbing on the wheel wells, etc. If you want to "fill your wheel wells", do it the right way, by getting suspension mods to lower your suspension. Don't do it the wrong way, by getting oversized tires.

If you're instead looking for better handling, which is the most common reason for getting bigger tires, you can do that the right way, by getting wider tires with the same outer diameter as stock tires, on wider aftermarket wheels, usually with larger diameters than stock as well.
 

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Holy Thread resurrection.
 

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In the world of tires, 3 percent is actually a very large difference. Small differences are around 1 percent or less.
I think you have a point there...after checking with the tire calculator, the sidewall on the 275 tire is 1/2 inch more....I think this means that the vehicle will actually be 1 inch higher off the ground....
 

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after checking with the tire calculator, the sidewall on the 275 tire is 1/2 inch more....I think this means that the vehicle will actually be 1 inch higher off the ground....
Nope. If the sidewall is 1/2 inch taller on the same wheels (as it is in this example), the vehicle will be 1/2 inch higher off the ground.

The "factor of two" you're thinking of is that the outer diameter is the more commonly specified measurement when comparing tire sizes. When the outer diameter of the tire is one inch larger, the vehicle is 1/2 inch higher off the ground. (The outer diameter is two times the sidewall height plus the wheel diameter.)
 
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