Tires.....A Pictoral Size Comparison, 18" Wheel Guys Have a look-see Options

[Fastbird]

Ok, knowing there's been some discussions on what size tires for what size 18" wheel that have been started by yours truly, I bit the bullet and spent some money to physically mock up some tires.

We all know that a 215/35-18 tire is as close to stock as it gets, but this leaves a lot to be desired in the ride quality and sidewall height, not to mention that a 215 is a narrow tire for most of the 18" wheels out there. This is what I had on our Celica before and a rim paid a very dear price because of this.

So.....Two sizes came to mind for a new tire. The often talked about 225/40-18 and a tire of my own conjuring, a 245/35-18. Of these, the 225/40 is much more common and quite a bit less expensive, but it also offers a greater inaccuracy of the stock speedometer than the 245/35 does.

Here I have pictures of two different tires mounted on my 18x8 HP Design Wheels HPR5's. They are 215/35-18 and 225/40-18. I managed to find a deal on a couple of used 225/40's to try out, but I haven't found a 245/35-18 to give a shot yet. Anyway, here's the pics and some commentary:

THis pic shows the overall tread width of the two (215 is low, 225 is high. For 10mm of tread with difference, the 225 sure looks wider.


Overall size differences: Yes, the 225 is a noticably larger tire. Speedo is going to be about 5.1% off from stock meaning a speedo reading of 60 when you're doing 63 MPH.



But here's the meat of the issue. Sidewall height and stretch. The 215 on the right/top has a noticeable sidewall stretch, severely exposing the wheel lip to all kinds of damages from things like New Jersey potholes (a moment of silence for my one trashed rim) or curbs or such. The 225 however, is nearly a flush line with the wheel lip with hardly any sidewall stretch. It IS still there though as I noticed when I laid my wheel down it was resting on the lip and not the tire.



Here's some numbers to chew on:

205/55-15 -- 4.4" sidewall, 75.0" circumference, baseline
215/35-18 -- 3.0" sidewall, 75.2" circumference, 0.2% slow, 60 MPH speedo = 60.1 real MPH
225/40-18 -- 3.5" sidewall, 78.8" circumference, 5.1% slow, 60 MPH speedo = 63.0 real MPH
245/35-18 -- 3.4" sidewall, 77.8" circumference, 3.7% slow, 60 MPH speedo = 62.2 real MPH

Now, looking at the 225 and how wide it looks, I don't think the 245 will fit in the wheel well very well without some massaging and clearance work. Yes, it's overall diameter and circumference will be smaller, but the width will cause problems I think. Another size that readily comes to mind is a 235/235 or a 225/35 as broken down below:

225/35-18 -- 3.1" sidewall, 76.0" circumference, 1.4% slow, 60 MPH speedo = 60.8 real MPH
235/35-18 -- 3.2" sidewall, 76.9" circumference, 2.5% slow, 60 MPH speedo = 61.5 real MPH

The problem with these is that the short sidewall will again cost ride quality and not offer a bunch of protection against sharp impacts like a pothole or something.

The 235/35-18 unfortunately isn't a common size at all, and the absolute cheapest tire in that size is going to run about $200 per tire, whereas the 225/40 can be had in a decent tire for a very reasonable $100-125 per tire. The 245/35 will cost about $160-200 for a decent tire.

My personal feelings are that a 235 width is going to be about perfect for an 8" wide wheel to just get the tire to extend out past the lip of the wheel, but to keep things sane in the overall size department you'd need to stick with a 35 aspect ratio as the 40 would be too big overall. I am trying to locate a 245/35-18 tire to test fit and see how it looks. The 225/40 looks great, but I'm not sure how the larger size is going to make the car look. Right now my inclination is going to be to go with the 225/40-18 because I was very surprised about how wonderfully the tire fits the wheel. I'm going to still actively look for a 245/35 but if I don't find one by the time I get the wheels back from being refinished, then I'll stop at that point.

Hopefully this helps people out. I've done a lot of searching on here for how different size tires look without finding good shots of how the tire actually looks on the wheel. That sidewall stretched euro look is absolutely silly in my book and aside from looking ridiculous, it puts your hard earned rims at risk. This post was meant to show how the size will realistically affect how the tire looks on the wheel and to offer a bit of education and help in choosing a tire size for you 18's.

[BloodyStupidDave...]

Excellent info. Anyone want to do a similar chart for 17"?

[Batman722]

that 215 on the 18" wheel is tiny, is the wheel 18x8 or 8.5 ?

[Celicav]

You would not have to stress about this is you just got 17s or smaller. But good research anyway. It's amazing how different the two tires look side-by-side. The 225-40 is logically cheaper b/c of the taller sidewall and better tread life.

[Celiracer18]

i had 215s on a 7.5" rim and it was stretched with that too. Sounds like 225/40 is the next set ill be getting.

[Fastbird]

that 215 on the 18" wheel is tiny, is the wheel 18x8 or 8.5 ?

That wheel is 18x8. That 215 was just a horrible choice, and admittedly I made it. Not again.

I'm not stressing over this at all. I'm researching and showing pics so that others can make a more informed decision when it comes to tires. Yes, I could have gone with 17's on the car and been done with it, but they just don't look as good as 18's do. Heck, I even considered going with a 19 initially but decided against it due to the car being a driver most of the time.

Dr. Tweak now sell the Dakota Digital SGI-5 speedo recalibration box. I have a bit of experience wiring in and calibrating these, so that will be my next write-up I do, the installation of one of those and a speedo recalibration for a 225/40-18 tire most likely (I'll be using a GPS based nav system for speedo verification).

Also stay tuned for an aftermarket heads up display installation within 3-4 months.

[Bricy]

With those rims and the 225's will you have to roll the fenders to get them in? Or would this not be a concern if your not lowered.

[lagos]

Are you really willing to sacrifice ride quality just so that at 60mph your speedo isn't 3mph off? I would get 225-40-18s or even 235-40-18s on there and roll the rear fender if needed.

I have 225-45-17s and my speedo is dead on with my gps, despite what all the online calculators told me it would be.

[Fastbird]

I "was" willing.....not anymore.

[playr158]

I've always had 225/40/18 on my 18x7.5" wheels (even on my celica) The speedo was BARELY off (maybe 1mph)

This post has been edited by playr158: Feb 13, 2008 - 1:49 PM

[Fastbird]

Nust ordered 225/40-18 Nitto NeoGen's.....now I have to decide to order 1 or 2 new wheels (ones bent, the others clearcoat is trashed on the lip) or try to do some manual labor and polish out the fubar clearcoat on the one.

[lagos]

Great minds think alike.... I JUST ordered Nitto NeoGens in 225-45-17 a few min ago too from discounttiredirect.

[6strngs]

if you think looking at a 215 and a 225 next to each other is a big difference, you should see a 245 next to a 225. it makes the 225 look like a baby I'd say it's a good inch wider.

I might do a side by side comparison like this but for 17's when I eventually get my wheels...

[Fastbird]

Great minds think alike.... I JUST ordered Nitto NeoGens in 225-45-17 a few min ago too from discounttiredirect.

Exactly where I got mine from! Decided to take advantage of the $25 on line discount and free shipping too huh?

if you think looking at a 215 and a 225 next to each other is a big difference, you should see a 245 next to a 225. it makes the 225 look like a baby I'd say it's a good inch wider.

I might do a side by side comparison like this but for 17's when I eventually get my wheels...

Yeah, I knew that would be the case. It would be interesting to see if the 245/35 would fit in there without a ton of rubbing or clearancing needed. Maybe I'll come across something within the next week or so on craigslist that I can snag for a price and do a comparo.

[jason]

i plan in trying to fit the biggest tire on my car come warm weather - also 18x8

seems the 245/35 seems to be the best for traction (largest footprint)

and the 225/40 seems to be the best for ride/noise (largest sidewall)

but .1" sidewall difference, and 20mm width difference, i dont think it would be much of a sacrifice for ride quality (25" for the 225/40 diameter vs 24.8 diameter with the 245/35)

ill have to try n fit some tomorrow if the weather is nice to see it all works. i imagine, the 245/35 should fit fine except a lil tight on the rear fenders - i have some room with a 35mm offset

[Fastbird]

i plan in trying to fit the biggest tire on my car come warm weather - also 18x8

seems the 245/35 seems to be the best for traction (largest footprint)

and the 225/40 seems to be the best for ride/noise (largest sidewall)

but .1" sidewall difference, and 20mm width difference, i dont think it would be much of a sacrifice for ride quality (25" for the 225/40 diameter vs 24.8 diameter with the 245/35)

ill have to try n fit some tomorrow if the weather is nice to see it all works. i imagine, the 245/35 should fit fine except a lil tight on the rear fenders - i have some room with a 35mm offset

Are you saying you've got a 245/35 that you're going to mock up?? If you could please post up pics like those I took. I want to see how the width of the tire is affected on the wheel.

[6strngs]

i plan in trying to fit the biggest tire on my car come warm weather - also 18x8

seems the 245/35 seems to be the best for traction (largest footprint)

and the 225/40 seems to be the best for ride/noise (largest sidewall)

but .1" sidewall difference, and 20mm width difference, i dont think it would be much of a sacrifice for ride quality (25" for the 225/40 diameter vs 24.8 diameter with the 245/35)

ill have to try n fit some tomorrow if the weather is nice to see it all works. i imagine, the 245/35 should fit fine except a lil tight on the rear fenders - i have some room with a 35mm offset

so you have an 8" wheel with a 35mm offset? me too but mine are gonna be 17's. let me know how those 245's fit. I have a feeling they might hit the shock in the front, but i dunno. so take lots of pics!

[Fastbird]

Oh man, this is a kick in the junk. HP doesn't make the Gunmetal HPR5 anymore and the ONLY place I've found them now wants $285 per wheel.

[Fastbird]

Well, the new tires arrived today. Just have to wait for the one wheel I ordered and then the shoes are going back on!

The Nitto NeoGen's are S-T-I-C-K-Y to the touch. I can't wait to try these out. They've supposedly got a pretty stiff sidewall, and hopefully that will help cure the really uninspiring turn-in that I was experiencing with the Exclaim UHP's.

[lagos]

You got yours quick. Mine wont be here till monday.