i know it affects your ride. a smaller ratio makes for a stiffer and
bumpy, etc. but how much larger and smaller than the stock 50 aspect
ratio can we go?

 

Sky's the limit baby! or www.tirerack.com for the lazy people

 

Tire diameter will effect final drive ratio and speedometer error.

 

whats final drive ratio?

and speedometer error, in my favor, or not?

can these be corrected?

 

Check it out:

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

And no, your speedometer cannot be adjusted.

 

i got -1.8%. so what does this mean in practical terms? and why is it so bad?

 

The key is to maintain the same diameter. If you go to a lower profile tire, your speedometer will read fast. When I had my mustang, I only had to buy an $8 speedo gear so it would read accurately again. Not sure on the Max though. If you go lower and not wider, your overall diameter will be lower; your speedo will read faster than you're going. As you move up a size in width, move down a size in aspect. That will keep everything pretty close. The TireRack is helpful as well. Hope this helps.

-MM-

 

that helps a lot! thanks dood.

 

Except for one thorny problem. The widest tire you can safely mount on the stock 7"-wide SE rims (if that is, in fact, what you're running) is 225 mm wide. So while it might be nice to move up to, say, a 235/45R17 or 245/45R17 tire from the OEM tire size of 225/50R17 in order to maintain the proper geometry, the rim width won't allow it.

Of course, you can always purchase wider rims.

 

do most people actually take all of this into consideration when buying new tires?!

is it that important?!

what are some repercussions of neglecting these factors?

 

Only the smart ones.


Is your life that important?

Perhaps the information under the heading of RIM WIDTH in the following article from Dunlop will shed some light on the subject:

http://www.dunloptire.com/tiretech/?...tire_width.txt

I'd suggest you pay particular attention to the words, " . . . could result in failure." Then ask yourself what some of the repercussions of tire failure might be, particularly if the failure occurs at high speed.

You might also want to check out the discussion in the following thread:

http://forums.maxima.org/showthread.php?threadid=107909

 

Most people just go to the tire store, buy OE size tires, have them mounted, balanced, and installed, and then just drive off without needing to know anything beyond how much it's going to cost. Since you list yourself as '1978' and 'student' I'm guessing that this is pretty much the extent of what you've observed.

But when you decide to change the size of your tires from what was offered as OE (either as std or optional sizes) you've just entered the world of vehicle design. Nissan's engineering group signed off on the OE tires after making their evaluations. When you deviate from those choices, you assume the responsibility of making an intelligent choice, especially since safety is so closely tied to your tires. You owe it to your passengers, other drivers sharing the road with you and even to yourself to consider all the factors. Expect to spend some time just finding out what these factors are. If this sounds a bit like doing a small research paper minus the word processing part, well, it probably should.

Norm

 

you are correct. the extent of my knowledge of cars of course is passed down from my father who does nothing but put original equipment back on. the typical "it aint broke why fix it" mentality.

i however, want to improve styling and handling with aftermarket tires and wheels, plus other modifications. the reason why i became a member of this org is to gather the information needed to make educated decisions about my maxima. its working out rather well... ive learned much in a short time.

 

Great post, Norm . . . accurate and compassionate. Anyone who is considering a decision to change the size of their tires would be well advised to review it.

 

Does it matter? Yeah...

Generally speaking, a lower aspect ratio tire, having a stiffer sidewall, makes the car handle better and a rougher ride. If you put lower aspect ratio tire on the same diameter wheels, you need to compensate with a wider tread width in order to have the same overall tire diameter and keep speedometer and ECU accurate. So long as you go with wider tread too, you can go as low an aspect as will fit your wheel's width. If you are also getting new wheels, then as low as is available (do they have 20-series tires and 22 inch wheels??)

Lower aspect ratio tires can look better... but really low ratios (like 45's or 40's) look go-cart unless you lowered the suspension.

Low aspect ratio tire leaves very little rubber between wheel and road; if you EVER let tire pressure get even a LITTLE low, potholes and parking lot bumps WILL damage tire AND WHEEL. Just check around the mall parking lot... find the cars with 45's on and look at all four wheels, how many have been damaged?

Buddywh

 

thanks for you post, dood. *nod* it helped me get a few more things clearer in my head.

 

Note to Y2kse: Before I begin this post, I want to make it clear that I'm not interested in starting up the debate again. I am only interested in eductating this person.

You will find many people have differing opinions on this. There have been many many many discussions about this very topic. I suggest you do a search for "tire size."

One side of the camp (y2kse) says that you'd be a moron to go to 235/45-17 on the stock 7" wheels because of safety issues (tread could separate from the tire). He may be right.

Another side of the camp (me and some others) say that YES, there are some safety issues that could possibly occur. However, I have not heard of one single incident of any safety problems with that setup.

It's my belief that all statements from tire manufacturers are just CYA (cover your ***) so they can't be sued if there is a problem. I personally run this tire size on the stock wheels and haven't had any problems. Whether you will have problems or not is not for any of us to determine. You might, you might not.

It's really up to you what you are willing to live with. I would recommend you buy a new set of rims that are at least 7.5" wide and avoid this whole mess. I didn't have the money to afford a new set of rims along with new tires, so I just bought the tires for now and when I have more funds, I will purchase wheels that are 7.5" wide or larger.

All I'm saying is be educated in your decision.

 

1. As you move farther away from 'just transportation' cars and into more sport related models, most of those owners do take alot into consideration...I think it is more focused upon by Max owners due to the oddball size of the OEM wheel and how limited our choices are in replacement tires...

2. & 3. Gotta agree with those comments made by others...

 

I would happen to agree that you can 'plus size' one step with the 7" stock 17" wheels. I had 235/45ZR17 Michelin Pilot XGT-Z4's on my '00 Max SE for 33K miles without a hitch and absolutely LOVED them. If it weren't for a big, ugly nail that chewed up one of my tires, I would still have them. I just switched back to the stock rubber since my lease is up in a few months.

If I get another Max, I will again switch out the tires to the 235 Pilots again. They increased the fun quotient on the Max by like 50%!

BTW, I also bought these tires from a friend of mine that owns a Tire Zone tire store in the Chicago burbs. He also agreed that going to 235's would be a no brainer.

 

hey! i go to school approximately 2 hours from chicago. would your friend be interested in making a deal for maxima.org members?!

 

For the owner of a tire store to freely recommend a tire and wheel combination that lies outside every tire manufacturer's acceptable limits borders on irresponsibility.

Does that mean that I would refuse to patronize his business? Not really. As an educated consumer I'd be going into the deal knowing exactly what I wanted and why (I'd walk right back out his door rather than accept substitution).

Would I place unquestioning faith in his tire and automotive opinions and suggestions? Not in this lifetime.

Norm

 

Note that 99% of the orginal poster's questions could have been answered pretty easily by clicking the link in the very first reply.

Norm, thanks for the well thought out reply. I'm sure this person learned quite a bit.

 

has anyone died from using the wrong tire?

or been "wrongly" sued in court?

 

Ford + Explorer + Firestone = deaths and lawsuits.

 

I am sure he would be more than willing to cut a deal for new business, maxima.org member or not. His is usually more than able to beat the pricing from the Tire Rack and then he will mount/balance them at a very reasonable price. You also then have get free rotations for the life of the tires and a place to go if you ever have a warranty issue (unlike mail ordered tires).

If you are interested, send me an e-mail and I will give you his information.

Thanks!

Norm ~ Tire Rack also provided the same plus sized recommendation of 235/45ZR17's for the stock rims. Car manufacturers would never provide such recommendations for fear of liability. To each his (or her) own.

 

wasnt it the tire that was defective? not an improper sized tire being put on?

of course, not considering that the "irresponsible" use of an improper sized tire is the defect.

Bridgestone/Firestone Tire Class Action

In In re Bridgestone/Firestone, Inc. Tires Products Liability Litigation, MDL Docket No. 1373, Lieff Cabraser Heimann & Bernstein, LLP, serves on the court-appointed Plaintffs' Executive Committee representing persons who own Firestone ATX, ATX II and Wilderness sport utility and light truck tires. Plaintiffs allege that these tires have demonstrated a tendency to suffer tread separation, which has been involved in accidents causing hundreds of serious injuries and deaths worldwide.

 

that would be soooooooooooo cool!! im saving up for new tires now and if he can give me a deal i cant walk away from he has my business, my chidrens business, their chidrens business, the business of all my seed.

 

You merely asked about a "wrong tire". Isn't a "defective" tire in the same catagory as "wrong tire"??

Odd, you went out and searched for this info but didn't click the tirerack link?

 

you mean this?

What is the right size for my vehicle?
Buying the correct tire size can get complicated, especially if you decide to upgrade from your vehicle's Original Equipment size. The expert sales team at The Tire Rack is always ready to offer performance and fitment advice. Call 888-541-1777.

A tire's first requirement is that it must be able to carry the weight of your vehicle. No matter how good a tire you select, if its capabilities are "overworked" just carrying the load, it will have little reserve capacity to help your vehicle respond to quick emergency. So when you are in the selection process, make certain that your new tire's size is designed to carry the weight of your vehicle! Don't undersize.

The other size consideration is overall tire diameter. Since many of the functions of today's vehicles are highly computerized, maintaining accurate speed data going into the computer assures accurate instructions coming out. And an important part of the speed equation is your tire's overall tire diameter.

For cars and vans, staying within a ±3% diameter change is desirable. Pick-ups and sport utility vehicles (SUVs) are usually engineered to handle up to a 15% oversize tire. Most tire dimensions can be calculated. For more information review the Tire Tech article, "Calculating Tire Dimensions." While at first a ±3% diameter increase or reduction in tire diameter may sound very limiting, in most cases it allows approximately a ±3/4" diameter change.

Additionally to help with the selection of substitute sizes, a system called "Plus Sizing" was developed. We use Plus Sizing to take into account the diameters of the available tires and the wheels, and then helps select the appropriate tire width that ensures adequate load capacity. Maintaining the tire's overall diameter helps maintain accurate speed data going.

i didnt get this far! heh, i got sidetracked by looking at the tires! thanks! this helps the most!!!!!!!!!!

so.......... correct me if im wrong, but because i got a -1.8% on the tire calculator and because on tirerack.com it says that for cars/vans that staying withing a + or - 3% is desirable means that there is no problem with me replacing them with these and that all of these "side effects" (speedometer error, etc.) will be minimal and acceptable???????

forgive me, im slow and most of all i dont want to #$%@#$^ something up!

 

Haha! Good job! Can't fault a guy who researches hehe

 

You are correct. A + or - 3% "give" in DIAMETER is generally considered acceptable. Notice, however, that there is no + or - 3% "give" when it comes to rim width. In fact, there's no "give" at all. If Tirerack.com was as unconcerned with maintaining proper rim width when upsizing as some of the people on this forum appear to be, don't you think they'd say so in writing? Or are you actually naive enough to believe that they just "forgot" to say something about it?

My advice remains the same. DO NOT ASK A TIRE DEALER IF IT'S OK TO MOUNT A TIRE THAT IS OUT-OF-SPEC FOR YOUR RIMS. Ask the manufacturer instead. And when you get your answer . . . and it will always be the same . . . ask yourself one simple question. If the manufacturer of the tire feels it's necessary to CYA, shouldn't you?

Never underestimate the power of denial!

 

If there has been debate on this in the past... well I don't want to start it again either but I want to make sure no body gets a misunderstanding from my previous posting... I stated you can go as wide a tire as you want (to get a lower aspect and keep speedo accuracy, but I want to emphasize the second part - "that will fit the wheels".

I strongly side with the camp that says do not fit a tire to an inadequate rim width. It is a safety issue so maybe there is margin on the specification - meaning you can many times exceed the specification without problems - but the margin is there for a reason. I am an engineer, I know some of the statistics and rationale behind establishing safety margins. I am not being a purist on this, I will many times exceed design margins myself when I want, but never a safety margin.

Again, don't want to re-open this debate. I just wanted to make clear my previous posting.

And... a little comment on the Explorer-Firestone issue. As I see it, this is a "safety margin" issue. The problems came about when the Wilderness AT tires are operated at lower air pressure than Firestone specified, which Ford wanted to for ride quality. If even that pressure was maintained there would have been no problems but since, as we all know, tires leak air constantly at a low rate... and people generally aren't very good about checking them... disaster. If Firestone had more margin in their design, and Ford hadn't recommended a lower tire pressure and therefore closer to the margin and spec. limit, maybe there would have been fewer accidents, deaths, and lawsuits.

Moral of the story... sometimes you can exceed safety margins, sometimes you can't! At least from my perspective.

BuddWh

BuddyWh

 

Thanks, Buddy.

I'm willing to exceed safety margins with respect to certain aspects of modifying a motor vehicle, but I draw the line at exceeding safety margins on my tires and brakes. My life is simply worth more to me than that. Others may do as they please.

 

My local dealer where I've bought tires in the past will not mount a tire to an incorrect rim width. It seems bead failures can happen when the tire is being inflated, leading to injury; I imagine their insurance requires this. The guy said he would sell me the tires, but I'd have to take them somewhere else to have them mounted. Interesting, I thought.

BuddyWh

 

Kind of gives one pause, doesn't it?