I am getting new tires, and just went to one of the tire places by me. After pricing out tires for my size 245/45/18 he told me that if i went 235/50/18 it would save a TON of $ and would cushion the ride a bit. Anyone have any negative thoughs about changing the size of the stock tires???

 

With the tires he suggested, your speedometer & odometer will be off but not by much. Over the long haul, your odometer will be off.

Also, are you saving just a few bucks per tire or a sizable chunk of change?

 

I would not make sacrifices like that. I went with 245 40 18's and I prefer the better handling. If I were to get new tires, i d probably go with 255 40 18 or 255 35 18. Im into handling and not ride quality, to an extent.

 

Definately do not go down a size. I would pay the money for the same size tire.

I have a SL so my tire size is 225/55/17 but I'm thinkin of getting a 245/50/17.

 

I have 22's on my car and the speedo didn't budge at all..

 

well..i could get the mich pilot for $518.00 all 4 out the door....and in the normal size they are about $1000.00 out the door...so ya ..its a big diff for the same tire. im not the biggest fan of the ride quality of my car..so i guess i dont turn corners too fast anymore so the ride is more important.......

 

Wow, yeah that would be worth considering.

Are you guys sure the speedo / odo would be off? As long as the outside diameter is the same this shouldn't matter...

 

thats plain bull. everything changed especially your performance.

 

get 245/40/18 or 235/40/18.

 

When your speedometer says are doing 60 mph with the new tires you will really be doing 61.3 mph. Check out the link to check out the differences.
http://www.miata.net/garage/tirecalc.html

 

I thought that the speedometer and odometer were electronically controlled (on the sixth gen.) now and could adjust to a different wheel and tire size?! Also because i'm not sure about what all the numbers on the tires stand for, how much thicker would the side wall be?

 

there is a Sticky showing the effects of diff. sizes.

 

I think you should definitely go for the cheaper tires, unless you have your heart set on the more expensive ones (which it really doesn't seem like you do). Your odometer from here on will read 100 miles for every 102 you drive... if that sounds like a big deal to you then you need a smack upside the head. Most (used) cars' speedometers are already off by 2% or so, if you really want to be nitpicky about it then just drive a little "slower" speedo-wise than you would normally... I mean it's nice to have a totally accurate speedometer and all, but is that extra 1.3mph going to get you a ticket? If the answer is yes, then account for it in your driving. Trust me, it's worth $500.

 

I second what MorpheusZero said.

235/50R18 will give a very slightly firmer ride and very slightly more ability to take sharp curves at speed than the 55 profile tires on the SL, but a very slightly softer ride and very slightly less ability to take sharp curves at speed than the 45 profiles on the SE.

As others noted, the outside diameter of the 235/50R18 is almost exactly the same as the 245/45R18. I feel you would be making an excellent compromise choice.

Please ignore any suggestions of a 40 profile tire. My son has had 40 profile tires on several vehicles, and they rode exactly like old western buckboards. If he drove over a peanut, I felt it. They may 'look fine', but you certainly would not want to go on any extended trips on 40 profiles, which, by the way, are far from cheap.


shadowfox - He is not exactly 'going down' a tire size. He is considering a tire with a width 10 mm narrower than the SE OEM and 10 mm wider than the SL OEM tire. But he is 'going up' 5% in profile. The outer diameter of the new tire will actually be very slightly greater than the OEM size. If you do go with the 245/50R17 when you replace the tires on your SL, I would be interested in how that works. If you like it, I might consider doing the same on my SL.


FrostMaxima - The '50' in the 235/50R18 means the sidewall height is 50% of the width of the tire, which is 235 milimeters. 50% of 235 is just a tad higher than 45% of 245 (the OEM 245/45R18 tires). If you actually try to measure the sidewall height, it is measured from the bead seat, not the visible sidewall. And the 'electronically controlled' speedo simply means the data is electronically transmitted rather than running the old cable to the back of the speedo. Changing tire diameter changes the reading.

 

Please ignore any suggestions of a 40 profile tire. My son has had 40 profile tires on several vehicles, and they rode exactly like old western buckboards. If he drove over a peanut, I felt it. They may 'look fine', but you certainly would not want to go on any extended trips on 40 profiles, which, by the way, are far from cheap.



fine dont listen to my opinion and keep your 4x4 size tire. that thing is huge. i drive on 245/40/18 on s-tecjs and illuminas on 3/4 and the ride is perfect. you guys are just wussies

 

well according to a tire calculator, your 40 profile creates a 3.64% difference in diameter which is way beyond any recommendations. Your speedo is 3.77% too fast displaying 62.2mph when going 60mph and clocking way more miles than you're actually going; 30 revs more per mile.

besides the possible rougher ride, you're at an even great risk of causing serious wheel damage. also the rim width range is beyond our wheel size. having a 7.5" width, why would we use a tire sized for 8-9.5" range?

 

where are you getting 7.5" from?
a smaller sidewall equals less flex in the sidewall which means better performance from the tire. but since you guys like your boats soo much with huge 4x4 tire go ahead. and like the saying "whatever floats your boat"

 

oem 6th gen SE wheels are 18"x7.5"

Where are you getting this 4x4 tire from? Since when do you go 4x4 off roading in low profile Ultra High Performance tires? And if you didn't like our "boats" so much, why do you feel the need to comment so much on them?

"a smaller sidewall equals less flex in the sidewall which means better performance from the tire." so why not run 30 profile? I mean smallest must mean best right?

 

did you ever look at the stock tire on a 6th gen max that has 18s? did you see how big the tire is? dont you see how high the car sits because of that tire? and goodyear eagle rsa are not low profile ultra high performance tires. they suck.
yes a smaller sidewall equals less flex but it has to be proportional with the size rim and the width.

 

YOU DON'T KNOW WHAT a 4x4 refering to max IS??????????????
you must be

 

..............................

 

um the ride height as in suspension mods? going from a 45 profile to 40 profile would not give you that much of a height improvement.

RSA are rated High Performance. No one is replacing their tires with these. I have Dunlops which are Ultra High Performance 245/45-18. Now how could these possibly be Ultra High if they are not considered low profile?????

you have shown no arguement why someone should choose a tire not designed to fit their wheel. 245/40-18 are NOT recommended to fit an 18x7.5 wheel. They are listed for 8-9.5" wheels and would cause too great of a circumference difference which I already listed.

 

I drive my car everyday dude, I know what happes to it, I've driven by speed traps and is not off at all... the rpms and everything is on point..

I only uped my diameter by 2", it hasn't changed...

they mentioned speed od, not performance, even with the rims my **** is not slow!!

 

ya i really agree about using 40's(the tire guy said he wouldnt recom. that size anyway) i dont want to worry about blowing out a tire every time i hit a bump. He showed me the exact tire i was getting and to be honest the "profile" didnt seem that much diff than the crappy goodyears on the car. I looked a little more and found some continental extreme contact tires for $164.00 a tire in the original size...and have read many, many, many positive reviews about them as an all season tire. The maxima isnt a race car anyway(in my opinion). so i dont think im gonna be taking it out to the track at all.......i wouldnt mind a little bit cushy'er ride......

 

just forget it willysmooo and take your kids bike...oh wait thats has tires on it to

 

dude did you notice that the 6th gens have that size? the 6th gen 18s are 18x7.5 and they have 245/45/18. going to a 245/40/18 is just shrinking the sidewall down. a 40 profile will make your car sit lower because the overall diameter of the tire is smaller.

 

the speedo does change. the easiest way to find out how much is to use a calculator. of course the rpm will be the same. the speedometer will be off.
and how much do your rims weigh? i know the stock 18s with the rsa on them weigh in at 52 pounds.i highly doubt that your huge rism with the tires on them are lighter then 52 pounds.

 

you just proved you have no clue what you are talking about. before you prove your ignorance further, look at the calculators in the STICKY.
dude did you notice that I wrote more than once that the 6th gens have 245/45-18?

Everything I wrote about the 40 profile specs is verified in both calculators. Tires are made of rubber. changing any aspect affects the entire tire. 245/40-18 is listed for 8-9.5 tires only and create MORE than a 3" diameter difference. It throws everything off causing more work for the car.

 

Nismo is right. The width of the tire in milimeters alone does not define the wheel width best suited to that tire. That is because the defined (maximum) width of the tire is wider than the wheel width the tire is on. That means the sidewall of the tire has to curve inwards as it approaches the wheel. A lower profile tire has less sidewall height in which to curve inward to the wheel and still turn back vertically in order to be seated firmly on the wheel's beadseat.

And those working diligently to lower their car are on a cosmetic ego trip. The OEM height (and ground clearance) of the Maxima is a carefully calculated compromise between performance and practicality.

Lowering the Maxima may make it look cooler while moving slowly in the 'hood, and may work at faster speeds on very good roads. But practical driving experiences require that the car also be able to traverse roadside curb cut ditches, transition from level roadway to steep driveway, travel on rough unpaved roads, etc. A lowered car has greatly diminished capabilities in those areas.

I prefer to use my Maxima as the great looking, sporty, practical transportation vehicle it was designed to be; at OEM height.

 

not sure what that kids bike comment is supposed to mean..but im 26 and dont have ny kids...i know you were trying to be funny, but i dont think its funny...but if you get a kick out of it..keep repeating it..........anyway...I got 4 245/45/18 conti extreme contacts for $758.00 otd..(road hazard and balancing rotation etc...cause i said belle tire would do it for 765.00..which they didnt..belle tire wanted 1012.00) anyway i bought 4 certificates from discount tire on my rs-a's(a while ago) and when i got home yesterday i noticed that i had a bubble in one of the rs-a's so basically i paid $534.00 out the door for all 4 today, cause i got 230.00 off cause of the bubble in the rs-a...what a deal!!! and these tires are soooooooooooooo much nicer riding then those goodyears..its night and day.

 

I also agree with Nismo here. If oem is 245/45-18 I would say to running 245/40-18. I think Nismo mistyped the:

This choice would create more than a 3% diameter difference or a 3" circumference difference, in either case not good.

vsamoylov
You have a 4th gen gle correct? If so, your oem was 205/65-15 and you went to 245/40-18. That is not a problem for your ride. These numbers produce .86% diameter difference no problems for a 4th gen gle, but would not be a good choice for a 6th gen due to the oem size.

 

I realized after I posted it and left it be. thanks for pointing that out.

I think a few people learned something from this, all that matters. Co-worker in the tire dept. also recommended I change my tire size to save $$. I considered it, but in the high priced brands, there was only about a $5 difference. I say if I see a $100 or more total difference, I would highly consider a tire as close to oem spec as possible. Personally, I would need to be w/in 1% maybe up to 2% if the price was REALLY good.

 

FTW:
1. Find out your rim width and what tire you want. Look at that tire manufacturer's website and official specs for "acceptable rim width" for the tire you want. Ideally, get the one in the "ideal width" column of the tech sheet.

2. use tire calculator, and determine the closest overall diameter to your stock. This will determine your aspect ratio (sidewall height)

3. Take the full size diagram (i.e. 245/45/17), go BACK to the tech sheet, and double-check that the tire WILL FIT within specs on the rim you have.

4. buying the wrong size tire to save a few bucks is As much money most people here spend on mods, $100 extra is not that much for tires that fit CORRECTLY.

 

Well, afetr about 600 miles on my new tires, all I can say is that anyone who is still riding on the RS-A GET RID OF THEM. I just cant believe how smooth and how much better the traction is with new tires. They actually grip in the rain!!! Everyday I drive my car, I feel like i am floating on a cloud and they corner SOOO MUCH BETTER than those GOODYEARS. As long as you get a good quality tire, I think you will be amazed at the diff. between new tires and those RS-A's. Sorry for posting like a dork, but I never thought I would ever be so happy with just new tires.

 

Your speedo is about 3 or 4 mph faster right now. Your new wheels are about 1.5" higher than stock. Thats why your car sits higher than a stock car. You are going faster than you think. Good thing is you have a higher top end.