Offset question

Ole Yeller · Post by **Ole Yeller** » January 7th, 2003, 11:36 am

I have tried the search and could not find anything,
Q. What offset is needed for15x7 wheels with 225-50-15 rubber. The car is lowered about 1.5" from stock and I do not want to roll or cut the lips in the fenders. Some say 38 and others 45 -- so what is right?

Cloudman · Post by **Cloudman** » January 10th, 2003, 9:53 am

You should be OK with 38 offset?

Ole Yeller · Post by **Ole Yeller** » January 10th, 2003, 10:31 am

Thanks Cloudman. I know that 225's are a tight fit on our cars and I'm about to buy some new wheels. It's such a bummer to get them and find out that the tires are rubbing. So what I'm looking for is someone who knows for sure! what offset is needed on 15x7" rims on a lowered car with out going to spacers or modifying the fenders, maybe it's not possible but I seem to remember posts on this subject --I just can not find them. Help Please.

nw98typer · Post by **nw98typer** » January 10th, 2003, 4:25 pm

I don't have a solid yes/no, but I'm hoping that I can provide some useful info.

I recently picked up my ITR from a fellow autocrosser. The car has 225 Victoracers mounted on Millenia rims which have a same offset as stock. When using the 225's, I need to run 5mm spacers so the tires won't rub. Based on my understanding of ITR's offset at 40-42mm, I think the 45mm offset would be the way to go w/o the spacers.

However... This does not take into account the fact that your car is lowered. My ITR is still at the stock height.

Perhaps a fellow autocrosser has experience with 225's on a lowered ITR.

97itr153 · Post by **97itr153** » January 15th, 2003, 6:28 pm

Lowering your car will NOT cause your tires to rub. This is because your tires/wheels will still be within their original range of motion. If your car didn't rub before, it will not rub now.

I have used 225/50 on stock rims and 5mm spacers with no rubbing. I don't know if the wider wheel will make the 225s rub since tires do tend to spread out when mounted on wider wheels. I know that 205/50 on a 38mm offset, 15x7 wheel does not rub anywhere.

If you do decide on the 38mm offset, I have a set of hardly used 15x7 Kosei K1 Racing wheels I can sell you.

salaxx@hotmail.com

paul98itr · Post by **paul98itr** » January 15th, 2003, 7:06 pm

I have a question about the spacers, I've heard about people only using the spacers in front, Is this recomended? When I get my type r, I want to run volk le37t's 17x7.5 with 40mm offset. On those I would like to plACE 225/45-17'S. I also would like to run the 5mm spacers front and back for better clearance. I was just woundering if I sould plan on all four corners with the spacers, or just front, or none. Thankx for the help.

nw98typer · Post by **nw98typer** » January 16th, 2003, 12:06 am

I'm afraid that I'm not really sure. I think it's a trial and error thing. If it were me, I'd plan on getting 4 spacers, just to be safe.

I have 4 spacers, and plan on using them on all corners when I autocross. It's my understanding from the previous owner that w/o the spacers it would rub. Regarding the spacers in the front only; I plan on running 205's at certain autocross events, and will probably not use the spacers there, perhaps that's what they are talking about.

NOTE: The lug nuts have also been replaced with some that are longer. I'm not sure if this is required for all spacers, but I wanted to mention it.

I'm sorry that I can't be more concrete, I hope this helps.

Ole Yeller · Post by **Ole Yeller** » January 21st, 2003, 2:57 pm

Thanks for your info ---- the stock offset on a ITR is +50--it is stamped on the inside of one of the spokes next to JJ15x6 and confirmed by my own measurments, I did some number crunching and came up with some interesting facts. Stock wheel with 205's--the rubber is wider by 5mm on each side from the 195's--obvious!! but now facter in an offset of +45 and you find that a 205 is 5mm narrower on the inside and 5mm wider on the outside, again obvious-- all we have done is move the wheel center line by 5mm to the outside. This fits--I ran this last year with no problems. Next we stay with the +45 wheel and put on some 225's and find that we are 10mm wider on both sides--makes sense right! So where does this leave us in comparison to a stock wheel and 195 rubber?
With +45 offset and 225's we are 10mm wider on the inside and 20mm
wider on the outside!
With +38 offset and 225's we are 3mm wider on the inside and 27mm wider on the out side! Thats more than an inch [ 1"= 25.4mm ]
So by the numbers it seems that you stand a better chance of having no rubbing with a 45 offset But! this is theory and in practice ???????
Hence I'm still looking for someone who can say--" I am running 15x7 wheels with an offset of ??? and 225 tires and it fits perfectly"----before I order my new wheels for this seasons autocross and track time.
Please and Thanks.

nw98typer · Post by **nw98typer** » January 22nd, 2003, 2:06 am

If you can hold off until this weekend, there's an autocross up here in the blistery NW. I'll look at the tires and see.

I'll probably also run into the previous owner, and I'll ask her for information.

Ole Yeller · Post by **Ole Yeller** » January 22nd, 2003, 5:46 am

nw98typer--- that would be great, I'm not in a desperate rush--we are up our ying-yang in snow here in eastern Canada and the temp is 0 degree's
so it will some time before we get back on the track.

descartesfool · Post by **descartesfool** » January 22nd, 2003, 9:33 am

I was wondering if the info you gave me was from personal experience or from what others had told you. On the thread I started for "ITR mods for a track day car", you said 225/50/15 would fit on 15x7 wheels with a 38 mm offset. As this is the tire size you and I would both like to run, I would also like to know if it really fits before I order the wheels. When I spoke to Tire Rack, they said a lot of people order just one wheel/tire combo to try out the fit and he said they will accept return if the tire is unsused. Client of course pays shipping both ways. As you and I are both basking in the snow and wanting to run at Mosport, customs clearance is a bit of an issue, but we can wait for the info. I also did a search on a few boards but was unable to find an answer. I also checked out Kosei's Japanese website and they have a new lighter version called a Kosei K-1 Racing TS version, just 4.9 Kg for a 15x7. I also found out that the Buddy Club P1 Racing is the same wheel as the Kosei K-1 currently being sold by Tirerack. Check out the site http://www.wheelspecs.com and search for wheels from 15x7 min to 15x7 max and less than 14 lbs. Then you can look at available sizes, offsets and weights.

Ole Yeller · Post by **Ole Yeller** » January 22nd, 2003, 4:31 pm

It was what other people told me--and the more I asked around the more confused I got. The best info so far is a 45 offset on the 15x7 --but it was
qualified by " you may have roll or cut the lip on the fenders for clearance" and since I am trying to avoid that if possible---hence the thread looking for the definitive answer from some one who has been there. So maybe we will get an answer after this weekend.

nw98typer · Post by **nw98typer** » January 28th, 2003, 3:29 am

Ole Yeller...
Here's what I got. The stock wheels are a 50mm offset, as you said. The Mazda Millenia wheels are 15x6 w/ a 50mm offset (I was wrong before). The 50mm was stamped and verified.

The 225's on the Mazda wheels w/o spacers, will rub both on the inner front wheel well (near the trans housing) and on the rear trailing arm. This comes from the previous owner, whom I trust.

With the 5mm spacers in place, I'm creating a 15x6 w/ 45mm offset, which works w/o rubbing.

Regarding the 7-inch width you're looking at, I think it's fine since you're adding 1/2-inch to each side of the wheel, but not affecting the 225 width which is more than the wheel.
The 225's w/ 5mm spacers stand proud of the side of the car, just a little bit. They look good and 'strong'. For this reason, I would not recommend the 38mm offset, which, as you said, add's a lot to outside dimension.

If you do decide to buy, and test fit them as Descartesfool suggested, here's what I'd do. Measure the distance from the hub center to the fender lip. Jack the car and remove the strut. With the car still in the air, mount the wheel/tire, and jack it up into position using your measured ride height. This will allow you to look all around for clearance with the car in the air and the wheel/tire in the correct position. If you leave the strut on, you won't be able to lift your suspension high enough (the suspension will compress some and then lift the car off the stands).

I wasn't able to run the race tires during the autocross, yes it really was that wet, but I really love the new R. I got the fitment info from a test fit I did on Saturday. I'll try to post pic's of the tires soon.

Sorry that I can't give you exactly what you're looking for, but I hope this helps.

Ole Yeller · Post by **Ole Yeller** » January 28th, 2003, 10:30 am

nw98typer--- thanks for the research, it does seem that +45 is the way to go. One point though-- a test fit as you described does not take into account suspension compression under heavy braking or cornering.
I spoke with the Solo 1 champion in Ontario CA. He runs a 45 offset but cut his fender lips down to nothing--- it seems I will have to do this or stay with the 205's-- [descartesfool take note] He did say that having a camber kit e.g. Skunk2, helps a bit since he has 2.5-3 degrees of neg camber dailed in at the front. This of course tilts the top of the wheel in towards the engine.--As for wet weather, I have had very good results with the Yok AO32R--can't wait to see what the new Soft Compound Yok will be like. Some people up here swear by the Toyo RA-1 at full tread in the wet. I have a post in the SCCA forum on this offset question-may we can get some more info there. Thanks.!!!

descartesfool · Post by **descartesfool** » January 30th, 2003, 12:49 am

Good info. I guess I will be getting the 15x7 wheels with a 45 mm offset and hope that the 225/50/15's don't rub too much. I plan to get a Skunk 2 camber kit for the front and an Ingalls camber kit for the rear, with 2-3 degrees neg. camber I think. Could you ask about alignment settings including front and rear toe? There are also light-weight wheels at a good price from Rota (Slipstream) and Team Dynamics (Pro Race). I did not check what offsets were available on these for the ITR. About the Yoko 032R SC (Soft Compound), there did not seem to be any info on the Yoko web site, although they are mentioned in GRM magazine. Do you know any more about them? I am really leaning towards Michelin Sport Cup, even though they are expensive, but Michelin says you dont have to shave or heat treat them, which makes their price more comparable to shaved and heat treated Khumos considering they wear longer in my experience.

nw98typer · Post by **nw98typer** » January 31st, 2003, 1:57 am

I did ask about the toe, and they weren't changing it from the stock setting. I have heard (grapevine) that some people run a little toe out in the rear for better rotation.

There aren't any changes to the camber either as the car is DS.

Regarding the tires, I don't have any knowledge. After spending last year on Azenis, it's going to be a learning year on the race tires.

descartesfool · Post by **descartesfool** » January 31st, 2003, 7:50 pm

My advice is tread lightly in the rain with R compound tires, if you haven't tried it! You will learn the meaning of aquaplaning. Street tires have way more grip in the wet than R compounds, particularly if the R's are worn or cold. On Michelin's web site, they recommend cutting grooves in the Sport Cup tires for the wet.