Edumacate on tire sizes

[Rally Man]

Edumacate me on tire sizes

Ok, so my new wheels got here. They are Enkei PF01 17x8 +50. Our OEM wheels are 17x6.5 +52.5. Our OEM tire size, according to Tire Rack, is 205/50-17. BUT when you see the recommended tire size for the Enkei it's 205/50-17! What gives? (scratch) I mean the wheel is 1.5 inches wider, yet Tire Rack is recommending the same size tire. Help? (screwy)

 

[ricksmz5]

The cross section of the 205/50-17 is 8.07"....I've been looking at similar size Enkei wheels, just not the $1000 ones like the PF01!...and was thinking of probably going to a 215/50-17, which is ~0.40" wider, and give you a little more bead grip. Here's a great comparison tool: http://www.discounttire.com/dtcs/infoTireMath.do

 

[Rally Man]

The cross section of the 205/50-17 is 8.07"....I've been looking at similar size Enkei wheels, just not the $1000 ones like the PF01!...and was thinking of probably going to a 215/50-17, which is ~0.40" wider, and give you a little more bead grip. Here's a great comparison tool: http://www.discounttire.com/dtcs/infoTireMath.do

See that's what I was thinking. The wheel is clearly wider so why stick with the same tire size? (screwy)

Oh and I got my PF01 for $800 shipped

 

[njaremka]

tire rack recommends 205/50-17 because that's the stock tire size. tire rack is funny that way. i would get 215/50-17 and call it a day. an 8" wide wheel will hold a 215 tire VERY well, and will handle nicely.

 

[MarkVII88]

I run 225/45/17 on a 7.5in wide rim with +45mm offset. This tire is a great fit. I think a 215 will be too narrow for an 8in wide rim unless you like the stretched look. It'll also cut down on sidewall height, hurting your ride too. I'd go 225 if I were you.

 

[Rally Man]

I would think even 235 would work no? I see the WRX guys run that day and night.

 

[MarkVII88]

235 would definitely work on an 8 inch rim, but being +50mm offset I'm not sure about clearance with shocks and struts. If I wanted to go with such a wide rim, I'd look for less offset, like +40 or +35mm.

 

[Silentnoise713]

235 would definitely work on an 8 inch rim, but being +50mm offset I'm not sure about clearance with shocks and struts. If I wanted to go with such a wide rim, I'd look for less offset, like +40 or +35mm.

ditto!!

Two independent questions.
-does tire fit rim?
-does wheel (tire+rim=wheel, +offset) clear fender and suspension of car?

Whatever tire you choose, check the tire mfg specs to make sure it meets the rim's min and max requirement. I'm not sure 205 would even fit 8" rims without it looking ridicilous (stretch look). stretch is meant to help clear fender (inward curve) for stance. our car's wheel well is not too big and the high stock offset doesn't give you much room without having to roll fenders or adjusting camber for clearance, which you cannot do up front with your setup.

 

[Rally Man]

For front camber adjustment I'd need camber plates, correct?

 

[crxgsr]

The 205 tire size will fit a variety of wheel widths.

You want to keep the overall rolling diameter to be as close to the original as possible.

So, from 205/50R17, you can use 225/45R17.

using a 215/50R17 or a 235/45R17 would also increase the tires height which generally is not recommended.

 

[MarkVII88]

What you say is true but it's no different than running a 205/60/16 snow tire. Overall diameter increase is about 2%.

The 205 tire size will fit a variety of wheel widths.

You want to keep the overall rolling diameter to be as close to the original as possible.

So, from 205/50R17, you can use 225/45R17.

using a 215/50R17 or a 235/45R17 would also increase the tires height which generally is not recommended.

 

[Silentnoise713]

For front camber adjustment I'd need camber plates, correct?

Correct. Unfortunately there is no aftermarket option for just the camber plate for stock spring mounts. There was one company who made a rudimentary kit but IIRC they stopped (prob not a very profitable business). Your best bet is http://www.vorshlag.com/index.php. I really want to dial in my alignment, which was a motivator to go CO setup. My research stopped at identifying Vorshalg without contacting them but if they do offer a solution, I would trade in the YS.

The 205 tire size will fit a variety of wheel widths.

You want to keep the overall rolling diameter to be as close to the original as possible.

So, from 205/50R17, you can use 225/45R17.

using a 215/50R17 or a 235/45R17 would also increase the tires height which generally is not recommended.

Just an example using the popular Conti DWS @ 205 wide x 17".
@ 205/45/17: Rim Width Range 6.5-7.5"
@ 205/50/17: Rim Width Range 5.5-7.5"
http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=ExtremeContact+DWS

In my bias opinion, best tool out there for tire calc is http://www.miata.net/garage/tirecalc.html. Use a GPS to calc your actually speed once you go with whatever tire. You'd just need to be mindful of the difference. Most cars speedo come a tad overly optimistic so a slight increase in overall diameter (decrease in speed reading) is not a bad thing but YMMV

 

[Rockin03mp5]

I'm pretty sure I upgrated to a 215/45 r 17 on my stock wheels. I would say with those wider wheels go with 225/45 r 17 if you can afford them. That would be the size I would go with on my 3 if I got those wheels, which I have looked at. Speeds have 225s from the factory and the 5 is just a fatter 3 anyways.

 

[Rally Man]

Correct. Unfortunately there is no aftermarket option for just the camber plate for stock spring mounts. There was one company who made a rudimentary kit but IIRC they stopped (prob not a very profitable business). Your best bet is http://www.vorshlag.com/index.php. I really want to dial in my alignment, which was a motivator to go CO setup. My research stopped at identifying Vorshalg without contacting them but if they do offer a solution, I would trade in the YS.

Wouldn't Corksport MS3 front camber adjustment plate work for our cars too?

 

[crxgsr]

What you say is true but it's no different than running a 205/60/16 snow tire. Overall diameter increase is about 2%.

Unfortunately, there is a difference.

I had a customer who purchased an oversized tire ~2% difference. When we put it on the vehicle, it was fine. When he drove it, it was fine. Unfortunately, he has a family, and so when the family gets in the car, the extra weight would cause the tire to hit the fender when cornering.

He couldn't live with them, and in the end, had to buy another set of "correctly sized" tires.

 

[MarkVII88]

I don't disagree that there's a size difference at all. whether it causes problems or not has everything to do with how much the oversize difference is and the wheel dimensions with offset. There's certainly an acceptable window on most, if not all, cars.

Unfortunately, there is a difference.

I had a customer who purchased an oversized tire ~2% difference. When we put it on the vehicle, it was fine. When he drove it, it was fine. Unfortunately, he has a family, and so when the family gets in the car, the extra weight would cause the tire to hit the fender when cornering.

He couldn't live with them, and in the end, had to buy another set of "correctly sized" tires.

 

[Silentnoise713]

Wouldn't Corksport MS3 front camber adjustment plate work for our cars too?

seems like they shold work and somone on CS's peoduct page asked the same thing for OE Mz3. These came out right around when I bought the YS. Nonetheless they are crazy/stupid expensive!!.. they don't show the spring seats but per description note that factory diameter spring is limited to up to 1.5 deg, while 2.5" springs can clear up to 3 deg.

FWIW, the CS plate look EXACTLY like YS plate, which is diff from BC. The cost of the CS plates alone is "almost" half the cost of the whole YS CO kit - yikes! You can get adjustable camber plates from BC and YS also but you would then need to source seats that mate to OE diameter springs and have proper size opening for factor shock piston diameter - this is what Vorshlag does. In the end, this route cost too much for me. If you didn't already know, you'd need to cut the shock tower opening if you want easy access.

Edit: Just to clarify I am NOT advocating COs!

 

[Rally Man]

If you didn't already know, you'd need to cut the shock tower opening if you want easy access.

According to CS you don't have to cut the shock tower.

 

[Silentnoise713]

According to CS you don't have to cut the shock tower.

yeah, I had to re-read what CS was talking about! Take a hard look at their initial plate design vs the new one. Their initial design could not be physically installed without enlarging the hole! The new version has the adjustment bolts recessed so it can be installed without enlarging the top. however, without cutting the top, it is physically imposible to reach the adjsument bolts. You would need to take the whole assembly out, set your adjustment by licking your finger and wiggle it in the air, put it all back together, then try again till you hit a rough acceptable measurement. You must cut which is why they provided an engineering/strength analysis to provide assurance.

 

[Rally Man]

Yeah I see what you mean.