Rim width (combined with offset, of course) does start to matter when you have 18" wheels. Knuckle clearance.

With that said, I have to agree that spending lots of money to end up on 225s seems, er, sub-optimal. But at least it wasn't 225s on a 9.5" wheel or 245s on a 7" wheel. So he ended up in the higher percentiles for this particular train-wreck thread.

I was worried about the rubbing in the rear. That's why i went with the 225's. A slight tire stretch, but nothing to be worried about. Ican also turn without any rubbing issues either. Over all, Im satisfied!

I would advise everyone against low profile tires for a daily driver. But that's just me.

Personally, I want the total width of the tire to be the widest (largest patch of grip), and the weight of the rim + tire to be the lowest. I also want it to look awesome and be inexpensive. Yes, I want it all.


I'm actually going to need help deciding on the size of my next wheels. I want something like 17x7 with the widest tires that will fit without rubbing. My car is lowered just 1".

Anyone have a similar ideal tire/wheel size already set up? I really need the largest contact patch possible on a 17" rim; I'm FWD.

I think I had calculated this years ago, but forgot. I thought it was 255's. hmmm... what's the other dimension?

jtmcinder said:

But at least it wasn't 225s on a 9.5" wheel or 245s on a 7" wheel.

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Because there's too much flex or something? Would an 8" wheel be better? Please help me understand.

Boostinsideways said:

I am sitting on 17x7 with 245/45/r17 and they are nowhere near aggressive.

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I looked at pictures, it doesn't stick out at all. OK, what happens I get 255's, do I drop it to 40, or what?

I'll have to read some of the guides posted here.

But I want the overall diameter to be correct - in OEM spec. I don't want my wheels to be too big around or too small... or do I? I always wondered that. Won't smaller wheels help me accelerate faster, at the expense of speed? I know it will put my speedo a little out of whack - and I'm talking about the car.

For every tire, there's an optimum wheel-width. Sometimes there are two optimums: one for lateral grip and one for longitudinal grip. They are often but not always the same. The trade-off is that wider wheels weigh more, which hurts for a variety of reasons. (This new fad of having "stretched" tires is rather silly, therefore.) The upshot of all of this is that most people should run a wheel that is 90-95% as wide as the tire. Thinner than this curls the sidewall inwards and kills lateral grip. Wider than this doesn't help (and can even reduce longitudinal grip) and weighs more.

jtmcinder said:

For every tire, there's an optimum wheel-width. Sometimes there are two optimums: one for lateral grip and one for longitudinal grip. They are often but not always the same. The trade-off is that wider wheels weigh more, which hurts for a variety of reasons. (This new fad of having "stretched" tires is rather silly, therefore.) The upshot of all of this is that most people should run a wheel that is 90-95% as wide as the tire. Thinner than this curls the sidewall inwards and kills lateral grip. Wider than this doesn't help (and can even reduce longitudinal grip) and weighs more.

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So by stretched, you mean that the rim is too wide for the tire.

I'm really desperate to get optimal grip. Again, I'm on a FWD car, which not only has much less drive grip, it launches to the rear of the car, taking weight off the drive tires. I won't even get into cornering while accelerating ... but that too

Wheel spin, and especially wheel-hop, is so incredibly undesirable. I expect to be putting down a lot more power in the near future, and I hope to be able to floor it in 2nd gear without more than a couple of little *chirps* at worst (once the tires are hot). I know there are other suspension mods that I will need as well.

Taking what you said as gospel, do you have an optimum tire/wheel size picked out?

This stuff is extremely expensive, so I don't want to make another mistake choosing. I completely screwed up on my $1400 set last time.

Thank you for your time

Additionally, the bigger you go, the more it costs. This is primarily why I have 17's. There is no way I'm buying 18" tires every year. I'll take that $2-500 elsewhere.

Nasty Dream said:

So by stretched, you mean that the rim is too wide for the tire.

I'm really desperate to get optimal grip. Again, I'm on a FWD car, which not only has much less drive grip, it launches to the rear of the car, taking weight off the drive tires. I won't even get into cornering while accelerating ... but that too

Wheel spin, and especially wheel-hop, is so incredibly undesirable. I expect to be putting down a lot more power in the near future, and I hope to be able to floor it in 2nd gear without more than a couple of little *chirps* at worst (once the tires are hot). I know there are other suspension mods that I will need as well.

Taking what you said as gospel, do you have an optimum tire/wheel size picked out?

This stuff is extremely expensive, so I don't want to make another mistake choosing. I completely screwed up on my $1400 set last time.

Thank you for your time

Click to expand...

Yes, stretched = too wide a wheel for the tire. It's the latest silly fad. Goes hand-in-hand with HellaFlush.

Optimize the tire and wheel for the type of grip you want; deal with other issues in the direct way. Thus, if what you care about is launching, run the smallest diameter wheel that fits over your brakes, so you can have the most sidewall. More sidewall also means less wheel-width is needed, which reduces the moment of the rotating mass. Then fix the wheel-hop with motor mounts and bushings, etc., and the appropriate alignment. Wheel-hop should not be fixed by running sub-optimal tires and wheels.

If you want to be able to turn, as well, then you'll have to compromise a little on the launch. With street tires (which have softer sidewalls than Rs), I like 245/40/17 on 2Gs with normal fenders and a need for the tire to tuck in. These are happiest on a 9" wheel, although an 8.5" won't reduce lateral grip too much. Some 245s even like a 9.5" wheel, but finding a light 17x9.5 in our offset isn't easy (and it'll cost a mint). If you run Rs, the old standard was 245/45/16 on an 8.5" wheel, again if you need it to tuck and can't make major body mods. I don't know if there's a new standard.

For all-out road-racing, you need to ask someone else. They all have wider tires these days and do what they have to get them to fit. I doubt there's a lot of people on 245s for that.

I run 245/40/17 Dunlop Direzza Sport Z1 Star Specs (commonly just referred to as "Star Specs") on a set of 17"x8" +38mm Evo 8 wheels.

No rub issues at stock ride height. I rolled the front and rear fenders when I dropped it ~1.5".

While a 17"x9" +27mm wheel would be awesome, you'll have fun trying to get that. The Star Specs seem very happy even on an 8" rim. I have to see if I can mount a GoPro low enough to shoot sidewall flex at the next autocross. With the -2.2° of front camber I run, they grip quite well and don't roll over the sidewalls with 42psi in them.

I just got a new set via UPS from Tirerack yesterday.

Maybe it's a 17"s vs 18"s thing, but the people who run Evo Xs in STU swear that both the Star Specs and the RS-3s are happier on 9"s than 8.5"s; several argue for 9.5"s. But, again, that's 245/40/18, not 245/40/17, although the sidewall is the same. And an Evo X weighs a bit more than a DSM.

With that said, when I was in STX way back when in a 2G DSM, I only had 17x8s and my 245/40/17 Kumho MXs seemed happy.

ps. knochgoon24 - do you recognize the background in my avatar? MidState Airport, north end

I didn't, but I recognized the username from LPAC. You should see the turns outs we've had recently.

I hope to be out at CPI this Sunday for some cone dodging. Pending my new timing belt gets here Saturday like STM says it should.

Does anyone know the name of the users that has the white eclipse with the 9.5 rims?

Dead thread!