How to decide on size of tires??

[aturcotte127317 10+ year member]

so the tires on my rims now are 225/45/(ZR) 17 i am not sure what the ZR is maybe someone can help me with that too? but my question is, if i want the tires to be more low profile, which of the numbers do i change?? (i am guessign the 45?) please any and all help, thanks!

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[revrider1 5,000+ posts]

I had some 205/40s

 

[fbi90909 5,000+ posts]

get low pros if you are lowering your car soon or if already lowered. that size rim with low pros on a stock height will look like shit.

 

[aturcotte127317 10+ year member]

i dont want really low profile, just a little bit thinner tire

 

[LOW ET 10+ year member]

yes the 45. the z is just the speed rating. the diameter of the tire will affect the speedometer so i wouldn't change the size to much. if you want a low profile tire with the same diameter you need to go to bigger rims.

 

[probmxstyle 10+ year member]

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46

 

[JimJ 5,000+ posts]

The ZR is the speed rating...higher than 168mph IIRC.

If it was a U, H, or V for example, it'd be rated for less.

 

[jdawg 5,000+ posts]

the first number is the tread width in mm, the second number is a percentage of how tall the sidewall compared to the tread width, so your tires are 45% as tall as they are wide, so in general is you want lower then yea get a 40 series, might help if I knew the car and if its lowered or not. the ZR is a speed rating, R means radial. Those tires are really sticky but they wear faster cause they are soft. I would get an H rated tire unless you want to buy new tires every year and a half.

 

[aturcotte127317 10+ year member]

alright thanks guys!!!!

 

[Adnan 10+ year member]

lol dude anything under 45 series = $$$$$ and a painful ride

i've seen a guy driving a tsx on 20s with 30...when i seen him pull up i could swear

i saw his rim lip touch the ground

 

[donpisto 5,000+ posts]

lol dude anything under 45 series = $$$$$ and a painful ridei've seen a guy driving a tsx on 20s with 30...when i seen him pull up i could swear

i saw his rim lip touch the ground

I beg to differ, it all depends on the suspension and the vehicle. Example:

I had an '01 Accord with Megan Racing coilovers dropped with about a 1 finger gap on stock 15" tires and hubs. Compared to my current vehicle, '06 G35 with Tein Basic coilovers with no finger gap and 20's on 245/35's, the G35 is a MUCH smoother ride, even when I had the Megan's on the softest setting the G35 is still a smoother ride.

Also, just an FYI, tire width makes a huge difference. I had 225/30's and they are exactly what you are describing, looking like you're riding on rims. Going with the wider tire mean less stretch, better protection, and a thicker looking tire.

The G35 as it is with the 20's and wider and bigger tires is still quite comfortable, even with the drop. When it comes to horrible roads, well, that's when you can feel it, but it's tolerable.

Here's pics of the G35 with 225/35/20's (not lowered)

Pics of it with 245/35/20 (lowered).

And for reference, here is the Accord when it was dropped:

As you can see, the amount of actual tire is MUCH thicker going from 30 to 35, but that has ALOT to do with going from 225 to 245 for the width since it is not stretched as much.

 

[edzy 10+ year member]

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

That calc is pretty cool. It will show you what the speedo will change to with the tires you choose.

I found it helpful when i added meat. was able to play around and get the speedo pretty close.