Tire sizes

right now I have 225/40/18's on my car and they are 9 inches wide and I want to get some BFG's next but I'd like to get some that are a little thinner sidewall and 10" wide. would a 255/35/18 be what I'm looking for? I have no idea how the sizes work either

225 is the width in millameter for the contact patch, 40 is the aspect ratio from the contact patch to the rim and 18, well duhh..

Reamber any aftermarket rims/tires will effect your wheel speed sensors, altering you MPH, but more importanly change your gear ratio!

Well I dont think it will change much considering I already have 18's and my spedo is dead on

Well I dont think it will change much considering I already have 18's and my spedo is dead on

LOL. Got me their.

My speedometer is dead on with my 17's too. I did that on pupose. Theres a couple formulas at www.tirerack.com (http://www.tirerack.com) that I used to figure out what size tire would be the same outside diameter of the stockers. My guess is you just happened to get one pretty close to or exactly the same size as the stock ones.

DO NOT GET 35'S!!!!!!!! i work at a tire shop and day in and day out were changeing 35's because they hit a pot hole and blew there tire out or ordering new rims because they hit a pot hole and cracked there rim NO LOWER THEN 40's!!! 245/40/18!!! trust me!

[QUOTE=scottsee]225 is the width in millameter for the contact patch, 40 is the aspect ratio from the contact patch to the rim and 18, well duhh../QUOTE]
actually you are wrong. to us yes thats it but the first number actually determins the highth and the 2nd number determins the width when they are makeing a tire just thought id share that....

i had to take tire class's before i could work there

The only reason I'm considering 35's is because fromt time to time my 40's look just plain to big lol I dont know how to put it but I want thinner, wider tires(my friend made fun of me for saying that:lol:) idealy I'd like something that is at least 9.5" wide but perferable 10"

well what width are your rims??? if your rims are wide enuff you could go with the 245

7.5"

[QUOTE=scottsee]225 is the width in millameter for the contact patch, 40 is the aspect ratio from the contact patch to the rim and 18, well duhh../QUOTE]
actually you are wrong. to us yes thats it but the first number actually determins the highth and the 2nd number determins the width when they are makeing a tire just thought id share that....

i had to take tire class's before i could work there


YOU ARE INCORRECT The 1st number is the width and the second number is the height. I worked at a tire shop for awhile before i got a kick ass job as a QA for trains

ok well let me make it easy, I want a tire thats 10" wide and low profile so what would be better a 245/35(40)/18 or a 255/35(40)/18?

yeah, i want to get some rims and tires, and i want wide tires, i've been looking into 18" rims, but i've been pushed away because of cost and weight... so... I'm thinking 17"x7.5" rims with 235/45/17 tires. how wide would they be? because i want them as wide as i can (400 WHP GST's need traction too...)

my 18's are pretty light, actually the tire weight more than my rims do

everyone has told me to get 17's For weight reasons... also, 17's are cheaper... so i'll just go with that unless i can find a killer deal... any input on my "setup"?

235 the 245 will be bluging off the tire

huh? you talking to me? i wanted 234/45/17 (tire size) however, i found some nice 18" rims for a decent price, so i may be getting 18"x8" rims, but i still want as much tread on the ground as possible, and i also plan on installing Tokico Illumina's i guess... droping down about... 1.5"? ish... if that matters... but whats your suggestion on tire size? like i said, i want as much tread on the ground as possible (IE - WIDE TIRES)

http://www.toyo.com/tires/tire_specsheet.cfm?id=18

Look down the tire sizes and then there will be a column for recommended rim width for each size. Also, I would recommend those tires, they grip great. Held 45mph s curves at 75+ no problem :grinyes:.

I have a question: Lower profile tires (on same size rims) make your speedo show a faster speed than you're actually going. But does you mileage go up faster too? Cause that would really suck. But what about cars with like 24" rims? They'd just never put on miles, lol.

Here's some info for you guys:

Tire ratings compiled from many reviews:
http://www.consumersearch.com/www/automotive/tires/reviews.html
If you look on TireRack they also have very good tire reviews. Look at the tests section.

Wheel diameter and speed difference calculator:
http://www.miata.net/garage/tirecalc.html

You gotta remember that that middle number (40, 50, etc) is just a ratio that is dependent on the width. So a 215/40/18 has a smaller sidewall than a 225/4018, even though the middle number is the same. So if you got a 255/40 the sidewall shouldn't have the blowout problems as someone said since the sidewall is probably thicker than stock (someone correct me if I'm wrong).

Personally I would get 50 series if I could do it again. I got 215/40/17's and you can feel every little thing in the road. And while that's a good thing in some ways, it also makes you have to fight to stay in the lane more than thicker tires. And you're constantly getting a massage from the imperfections in the road (and I have stock suspension). I'm also going 56 when my speedo says 60. And I can't use my spare anymore unless I want my differential to blow up (tires can only have 3/32" difference according to Mitsu). Also my car looks like a 4x4 with it's 3.5" wheel gap. But they do look nice...

the comment about blowing out tires with a 35 series, is bullshit

ive driven 2 vehicles with 215/35/18's for more then 2 years without blowing a tire due to the size.
i did blow a tire because of severe negative camber, and it just ate the inside of them