I'm running an 05 Forester XT, others have run 245/40/17 Hoosiers so I know I can stuff wide tires without rubbing issues. My question is about the trade-off between wide tires and lightweight wheels. Am I better off running lighther wheels VS heavier wheels that can handle wider tires ?

I have a line on some Enkei RFP1 17x7.5's or could buy new 17x8's from discount tire for $136 shipped each(MB Weapon which are sold in Japan as Final Speed "Eraser"). They weight about 19-20lbs. The Enkei's are something crazy like 15lbs each. I'd love their 17x8's but that's $1100 to buy new.

http://www.discounttiredirect.com/direct/findWheelDetail.do?wd=17&pc=53635&rw=8&bp=5-100&tc=MBMWEA

Obviously the 17x8 can take a wider wheel. I'm planning on running at least a 235/40/17 RA-1 and I'm unsure if it will fit the Enkei 17x7.5 wheel. In the end, I am wondering if I am better of running a smaller tire with a much lighter wheel or a wider tire with a heavier wheel.

These will be purely track wheels, 90% of the time used for Solo II events and then track days (and possibly Solo I down the road)

You can run a 235 RA-1's on your 7.5" wheels. They run narrow compared to other tires.

The next step up RA-1 is a 255, so you should move to 8" wheels if you think you want to go that big.

This is something I've been wondering about as well. I've been seeing some of those sweet, tasty SSR 17x7.5 on the classifieds, and I think they run 13-14 lbs each. On the other hand, there are some good, cheap-ish (5zigen) 17x8's that are around 18 lbs each. Assuming the tire selected could be mounted on either rim (whether it's 'recommended' or not), which would you choose?

I guess it comes down to ~4lbs less per corner vs. the extra response/grip the wider wheel provides...

If you look around you can get the rpf1 in 17x8 for $960 + shipping. That's the lowest I've found them for recently.

To the OP, where are you located??

I know it sounds crazy but you can run 275/40/17 on RPF1(or others of course) +35 offset, 17x8. It has been done and will be done on another car this week;)

For your 7.5's I would go with the 245's, you will be fine as long as the offset is ok and the weight savings are far more important than most seem to fully understand.

R1-A are not going to be your optimum autocross tires, I do not know about their track day performance though.

I have a very modified yet very streetable FXT, 05 in fact! I will be running Bridgestone RE-01R in 245/45/17 on 17x8.5 Volks(very low weight) for street and track days(it is not really a race;)

I will be running V710's on my RPF1's, 17x8, 35mm for autocross and/or time trials and Solo 1's if any scheduled around here.

I would love to have 17x9's for the V710s and have determined(at least 95% that is) with a +35mm offset the would fit but I am not willing to spend that kind of money on 4 wheels that would be low enough in weight.

I can get some dirt cheap, strong 17/9's, great wheels but 22lbs, I would rather run my 15.6 lb 8" wide wheels instead.

Rick

Rick

For a torquey car like yours I don't know how much wheel weight really matters. 17-18 is average, 15 is definitely on the light side, 19-20 is heavier but not terrible. A car like the Miata is a lot more sensitive to it. I think the $$ saved on lighter wheels can be put towards better things in your case (like V710's instead of RA1's for instance)

john

To the OP, where are you located??


For shipping purposes 13669 (upstate NY) Why ?

- Rick, look at my username. Think "forester forums" Same guy there

Hey Leg! See you on the Forster forum!:):)
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Other factors to consider in weight besides how much power you have is the ability to brake well and keeping your tires well connected to the track. Lower weight allows the suspension to do it's job much better;)

If you have ever A/B tested the same car, same setup, same tires, different weight wheels you would be suprised at how big the improvement can be.

But, anything in the 18 lb range is going to be fine, 19-20 is the upper limit I would consider, over 20 is just to heavy, in my opinion of course:)

Rick

If you look around you can get the rpf1 in 17x8 for $960 + shipping. That's the lowest I've found them for recently.

Linky ?



I know it sounds crazy but you can run 275/40/17 on RPF1(or others of course) +35 offset, 17x8. It has been done and will be done on another car this week;)

I'll wait till you put those your FXT, I doubt they'd fit :D


For your 7.5's I would go with the 245's, you will be fine as long as the offset is ok and the weight savings are far more important than most seem to fully understand.

R1-A are not going to be your optimum autocross tires, I do not know about their track day performance though.


So you are positive I can fit 245 R comps on a 7.5 wide wheel without bulging out ? And thus totally positive a 235/40/17 RA-1 will fit then ? And yes, I'd like to stay as light as possible where possible. 8 inch wide wheels typically aren't light (save for the enkei's and a few $$ others).

From my experience V710's are the best but wear quickly. RA-1's are much better than the A032's I've usually run and they still last long enough. I'd prefer to give a little traction for extended life. Also, these will see lapping days which totally kills V710's.

Linky ?





I'll wait till you put those your FXT, I doubt they'd fit :D




So you are positive I can fit 245 R comps on a 7.5 wide wheel without bulging out ? And thus totally positive a 235/40/17 RA-1 will fit then ? And yes, I'd like to stay as light as possible where possible. 8 inch wide wheels typically aren't light (save for the enkei's and a few $$ others).

From my experience V710's are the best but wear quickly. RA-1's are much better than the A032's I've usually run and they still last long enough. I'd prefer to give a little traction for extended life. Also, these will see lapping days which totally kills V710's.

I'm ordering them right now from Import Image. They are even cheaper than $960 + shipping now, for 17x8.

I will be putting 275/40 Kook z211's on them.

I ran 245's on my 17x7.5. Speed signs match my speedometer reading with this tire size. 235/40-17 will spin a little too fast and indicate you are going faster than actual. I would go with 245/40 if I were to stick with 17's. I'm actually going to try out 18x8's with 245/40's or 235/40's on my FXT since our OEM tire size is bigger than our little brothers (wrx'x, sti's). Mine are still for sale if your're interested.

http://forums.nasioc.com/forums/showthread.php?t=1198862

As stated by Rick, 17 x 8 w/ 275-40-17 Kumho 710's do fit. Close, but doable, you need to monitor your fender liners and ride heights of course. I have rubbed a little plastic away. Not bad though.

See link for a recent photo....

http://public.fotki.com/makofoto/2007-solo-solo-2-au/scnax-cscc-champ/20070401708.html

I ran 245's on my 17x7.5. Speed signs match my speedometer reading with this tire size. 235/40-17 will spin a little too fast and indicate you are going faster than actual. I would go with 245/40 if I were to stick with 17's.***********For R-comps, who cares if your speedometer is right?? You aren't planning to daily drive on them, are you??

As stated by Rick, 17 x 8 w/ 275-40-17 Kumho 710's do fit. Close, but doable, you need to monitor your fender liners and ride heights of course. I have rubbed a little plastic away. Not bad though.l]

Are you saying I could squeeze 275's on my FXT ? If so, wow. On mine I'll soon have 04 STi take-off struts + JDM pink springs + Group N top hats. Think it will work ?

What kind of offset are we talking ?

Are you saying I could squeeze 275's on my FXT ? If so, wow. On mine I'll soon have 04 STi take-off struts + JDM pink springs + Group N top hats. Think it will work ?

What kind of offset are we talking ?

I've seen Kumho V710's 275/40 17's fit on the Stock 17x8 wheels on an 2005 A Stock STI here in my region. No rubbing.

...and I cram 245 V710s on my stock 7" wide wheels for DS.

For R-comps, who cares if your speedometer is right?? You aren't planning to daily drive on them, are you??

For autocross, it may be a diiference between staying in the same gear or having to shift up one to stay out of redline. It could be as much as one second shifting up and another shifting back down. Autocross racers look for that fraction of a second to win...they care.

Are you saying I could squeeze 275's on my FXT ? If so, wow. On mine I'll soon have 04 STi take-off struts + JDM pink springs + Group N top hats. Think it will work ?

What kind of offset are we talking ?

I am running Megan Racing CO's, The wheels are RPF1's +35
BTW I am ploney on sf.org :)

Your suspension combo. won't work, the bottom spring perch will be in the way. I posted pictures somewhere over on sf.org under motorsports a while back.

Hey Legacy, I have the Enkei RPF-1s 17 x 7.5. Great wheels but it would be questionable to squeeze Toyo RA1s in the 235 size on them because of the tire's width. R-Compounds run wider than street tires of the same size. If you're tracking you want the sidewalls to be flat not bulging. You're going to compromise handling and reduce tread contact on the track if you put too large of a tire on a wheel. I was able to squeeze Hankook Ventus Z212 in the 235s on them but their width is much less than the Toyo RA1s.

My track wheels are 17x8 Rota Slipstreams with the Toyo RA1 235s on them. They fit nicely. They are noticeably heavier than the Enkeis but the Slipstreams are sturdy wheels and I got them for a great price. If you're doing time attack track sessions, I don't think the weight is as much of an issue because you don't experience as many abrupt changes in speed as you would in auto-x. If all of your tracking is auto-x, I think light weight wheels become more important.

If I had more money I would have gone with the Enkei RPF-1s in the 17 x 8 size with 45 et offset. I like their look and they are lighter than the Slipstreams. The RPF1s are not as sturdy as the Slipstreams, however. I bent one of the RPF1s when I dropped a wheel off the track. Fortunately, I was able to have it fixed.

For autocross, it may be a diiference between staying in the same gear or having to shift up one to stay out of redline. It could be as much as one second shifting up and another shifting back down. Autocross racers look for that fraction of a second to win...they care.Hum, there's a small chance I may have an idea what autocrossers look for. :lol: Your post was talking about keeping the speedo the SAME as stock though, and rarely do autocrossers care about that. Just about:
1) Being in the power band for as long as possible. While also:
2) Minimizing the number of shifts

It's not the autox "tire to have", but the RA-1 is great for track days, a forgiving tire that wears fairly well and sticks pretty well once warmed up.

Hum, there's a small chance I may have an idea what autocrossers look for. :lol: Your post was talking about keeping the speedo the SAME as stock though, and rarely do autocrossers care about that. Just about:
1) Being in the power band for as long as possible. While also:
2) Minimizing the number of shifts


My hats off to you Mrs. Croy. I was just informed (about 10 mins ago) that you are the top female autocrosser in the nation. I had no idea... In any case, I think we are in agreement about minimizing the shift, right?

Good info here guys/gals, keep it coming. It appears obvious that any wheel I purchase might as well be 17x8 since I can run the wider tires and obvioulsy the more weight I can save the better. I think the Enkei's represent the best bang for the buck at their current price.

Wow Jen! Top female autocrosser! Nicely done!

:)

My hats off to you Mrs. Croy. I was just informed (about 10 mins ago) that you are the top female autocrosser in the nation.Well, then you were drastically misinformed. :lol: I'm not even the top female autocrosser on NASIOC (IMO, that title would go to CamaroFS34), much less the nation.

I am a halfways decent autocrosser though, IMHO. :cool:

In any case, I think we are in agreement about minimizing the shift, right?Yes. Agreed.

I think the Enkei's represent the best bang for the buck at their current price.That's my feeling (and apparently the feeling of a lot of others as well). They're lightweight, they're strong (for cast wheels), they're the "right size" and have an appropriate offset, and they're cheap. Score!