specific tire models and wheel size, 225/50R15 tire rub with +38? DC2 rear

[court76wi]

I have a DC2 Integra that I'm looking at running the following tires on my car next season in a 225/50R15 tire size. BFG g-Force R1 Kumho V710 Toyo RA1 I currently have two sets of Kosei K1s, 15x7 with +38 offset. I successfully ran some used 225/45R15 Hoosier R6s last year without any problems. I did some searches, and tire types and wheel sizes are going all over the place. I've heard some clear, some rub, etc. It sounds like it's close depending upon the tire and rim width. I'm just curious with 15x7 wheels, and 225/50R15 tires in the above brands. If anyone running these configs had rubbing issues with +38 offset. If I need to run wheel spacers so be it, but if I won't have any problems that's even better. I'm mostly concerned with the rear trailing arm. Everything else should clear as far as I know. I'm about 5.5" off the ground and approx -1.7 degrees camber in the rear. Fenders are rolled, so no sheet metal issues. The 92-95 Civic has the same rear suspension clearance as the DC2 doesn't it? Appreciate any feedback.

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[powerneedy]

i am on 15x8 +36 and no rubbing but im on a super stiff spring rate... for reference though you will be 14mm more inward just on the rim i would think you will clear no problem unless you are super low in the wheel arches...

[Stinkycheezmonky]

With the RA1 and V710 you'll be fine, I've had both of those on an Integra on that same wheel. You might have the tire rubbing the rear trailing arm just a little under hard load, but not anything worth worrying about. Can't say for the R1 as I haven't used them.

The EG Civic and DC Integra have the same trailing arm clearance, but the fender clearance is a bit different; the Integra has a slightly lower fender edge I think, and more opportunity for rubbing. Both really need to have the lip rolled, but you've got that taken care of.

[court76wi]

Cool, thanks guys. Anyone running a BFG R1 with a similar setup?? I know someone running a R1 with the same wheel size on an ITR, but of course different suspension clearance in the rear.

A 15x7.5 or 15x8 wheel would be nice, I'm restricted to a 15x7 max though...

[slammed_93_hatch]

Originally Posted by court76wi

Cool, thanks guys. Anyone running a BFG R1 with a similar setup?? I know someone running a R1 with the same wheel size on an ITR, but of course different suspension clearance in the rear.

A 15x7.5 or 15x8 wheel would be nice, I'm restricted to a 15x7 max though...

Its fine. We ran them on a del sol and it was fine.

Really your not going to have much trouble running anything most tire mfr offer in a 15" (excluding the 235R888 and the 255A6) on a integra/civic.

[nsxtasy]

Why not keep using 225/45-15? There's no advantage to the 225/50-15 over the 225/45.

[slammed_93_hatch]

Originally Posted by nsxtasy

Why not keep using 225/45-15? There's no advantage to the 225/50-15 over the 225/45.

several tires are only available in 225-50-15.


And i know a handful of racers that i race against that swear there is difference in both lateral grip and in acceleration when you are talking about a tire like the Ra1 which is offered in both sizes.

[Stinkycheezmonky]

Originally Posted by court76wi

I know someone running a R1 with the same wheel size on an ITR, but of course different suspension clearance in the rear.

Why would clearance be different?

Also, Ken, I know some K-series guys that prefer the 225/50 for the slight bump in gearing. Seems to help them put the power down a little better. Like Jimmy said too, I think the V710 is only available in 225/50.

[gabebauman]

Hoosier seems to be the only brand that comes in 225/45/15
http://www.tirerack.com/tires/TireSe...er=15&x=56&y=9

Way more brand options for 225/50/15, (Hoosier also makes them in the 50 series)
http://www.tirerack.com/tires/TireSe...er=15&x=36&y=8

[slammed_93_hatch]

Toyo Ra1 comes in both 225/45/15 and 225/50/15

R1 only comes in a 225/50/15

Goodyear RS only comes in the 225/45/15

Hoosier R6 comes in both

toyo R888 comes in both

[nsxtasy]

Originally Posted by slammed_93_hatch

i know a handful of racers that i race against that swear there is difference in both lateral grip and in acceleration when you are talking about a tire like the Ra1 which is offered in both sizes.

Originally Posted by Stinkycheezmonky

I know some K-series guys that prefer the 225/50 for the slight bump in gearing. Seems to help them put the power down a little better.

I think you both have that backwards. The larger diameter of the 225/50 will actually hurt your acceleration in any particular gear (like putting taller gears on your car); the "bump", if any, helps with smaller diameter tires, not larger ones. Of course, gearing differences may help you on some tracks, may hurt you on others; usually smaller diameter tires, like the 225/45 in this case, help as long as they don't force you into additional upshifts, but hurt if they do.

As for lateral grip, it too is typically better with shorter sidewalls, IOW better with 225/45 than 225/50.

And, of course, there are fewer worries about rubbing with the additional 10 mm of clearance of the 225/45 (the sidewalls are about 10 mm shorter than with 225/50).

[Stinkycheezmonky]

Oh, I understand the basic shorter tire = shorter gearing concept. I'm just going off what they said (they also understand that concept). Not sure why it works, but it seems to. The "bump" might be to make them just a touch longer and kind of "tame the beast" or something.

[nsxtasy]

< shrug >

One thing about track tires - as long as they don't cause any severe problems (e.g. rubbing), just try them out. If you don't like them for some reason, you'll use them up soon enough anyway, and you can just try something different next time!

[slammed_93_hatch]

Originally Posted by nsxtasy

I think you both have that backwards. The larger diameter of the 225/50 will actually hurt your acceleration in any particular gear (like putting taller gears on your car); the "bump", if any, helps with smaller diameter tires, not larger ones. Of course, gearing differences may help you on some tracks, may hurt you on others; usually smaller diameter tires, like the 225/45 in this case, help as long as they don't force you into additional upshifts, but hurt if they do.

As for lateral grip, it too is typically better with shorter sidewalls, IOW better with 225/45 than 225/50.

And, of course, there are fewer worries about rubbing with the additional 10 mm of clearance of the 225/45 (the sidewalls are about 10 mm shorter than with 225/50).

Really its personal preference.

But several racers like the taller tire.

It helps with gearing, for them. And girp, for them.


user brianz and mikeski38 love and are faster on the 50series then they are the 45s

[court76wi]

For myself, as someone else mentioned above, two of the tires I'm interested in are available in 225/50 only, so as far as the RA1 is concerned I'd rather just keep everything the same.

I won't comment on grip, because I don't have enough experience, but a 225/50 tire just fits better on a 7" wide rim than a 225/45. The 45s tend to "doughnut" on a 7" rim. Taller sidewalls are also generally more consistent and less edgy than shorter sidewalls in terms of handling and "forgiveness" to a certain extent. Too small a sidewall can hurt handling, and too large a sidewall can hurt handling. Again though, I can't comment between the two saying one is better than the other at this size. I'm no expert.

As far as acceleration is concerned, I'm running a 4.928 final in my transmission. So it doesn't bother me that much. In fact I'd like to get just a touch more top end back out of each gear so a 50 will help there. Not a lot, but a little bit. If I was still running a 4.4 final then I might reconsider. That's just me though...

Slammed_93, was that a +38 offset you were running on your Del Sol?

[ScottBell]

We had a thread about this a while back. With a 225/45 Hoosier on a 15x7 you need +43 or less offset to keep from hitting the RTA. The Hoosiers are wider than any of the tires you are considering, so you should be fine on inside clearance. I can see where a 50 series tire on a +38 might have some problems with fender clearance.
The best thing you can do is get a worn out tire in the size and brand you want and test fit.

[seek167]

Originally Posted by nsxtasy

I think you both have that backwards. The larger diameter of the 225/50 will actually hurt your acceleration in any particular gear (like putting taller gears on your car); the "bump", if any, helps with smaller diameter tires, not larger ones. Of course, gearing differences may help you on some tracks, may hurt you on others; usually smaller diameter tires, like the 225/45 in this case, help as long as they don't force you into additional upshifts, but hurt if they do.

As for lateral grip, it too is typically better with shorter sidewalls, IOW better with 225/45 than 225/50.

And, of course, there are fewer worries about rubbing with the additional 10 mm of clearance of the 225/45 (the sidewalls are about 10 mm shorter than with 225/50).

225/50 will help the k guys out cus getting on it im spinning 1st and 2nd on my a6 with a 4.3 fd . needless to say i learned throttle control well this year and a6 cost alot of money

[kommon_sense]

For the k-guys, I doubt they spend much time in 1st or 2nd on a roadcourse. I rarely hit 2nd w/4.389 FD. I doubt that I would ever hit it with a shorter FD. Can't speak for auto-x.

[The Destroyer]

Ive had the 225/50 RA1 on +43 7" wheels. It barely rubbed the rta under hard cornering and also rubbed the quarter panel, they needed slight rolling.

[seek167]

yeah auto x for me needed to step up to the 275/35/15

[court76wi]

Boy, I don't know about a 225/45R15 Hoosier clearing with a +43 offset. I ran those at my last race with a +38 and there wasn't much space left. I had to use a tape measure to slide between the tire and the RTA to make sure it was good. That's too close to comfort for me.

The A6s might have a different sidewall than a R6, be here's a quote of an A6 rubbing with a +40 wheel...

225/45-15 Hoosier A6's on 15x7.5 et40 Slipstreams DO rub the rear trailing arm slightly. We use 3mm spacers in the rear for autocross.. not sure I'd run spacers on stock rear studs on the track.
I've test fitted 225/45-15 A6's on 15x7 et38 K1-TS and they did CLEAR the rear trailing arm barely.

Of course with AutoX you genreally get more tire flex than on a road course. +43 might clear, but that's got to be pushing it...