Hey guys.. my new 960 wagon has arrived and the messing around starts.

Here is my problem...


They are Moda R6 18x8. I think the offset is around 45mm (if I measured right). I'm thinking i'd have to run skinny rubber if I'm going to clear the strut.. but I'm no tire pro.

So do you think I could get away with a 215/40/18? Or should I stick a small spacer in there? Do you guys still sell thin spacers I could put in there?

Who need spacers Geoff, just notch the strut

8 inches wide is 203mm, so go with a 205 tire, or get a spacer and go with whatever you want

- R

960s have FWD offset wheels, but I think they're more like 38mm at 7" wide. You've added another 7mm of offset (towards the strut) and another 13mm of backspacing on top of that, so your rim is about 20mm closer to the strut. Still, going more than 7mm would alter your steering geometry and would possibly give you more steering feedback (good) and wander (bad).

Running it like that would probably be really bad, unless you ran tape weights and kept tires with rim protectors off the wheel. You could probably run 235 tires otherwise, but with a 1/4" spacer you'd probably be more comfortable.

I had bolted on my 17" pegs on there with 235/40/17s, actually had it on the ground and went to pull the car out... when I dropped it into reverse the car didn't budge.. gave it some gas and it made some terrible rubbing noises. My first thought was *what do I have to cut to get these things to work!*.




I'm thinking 205s is too skinny.. spacer it is.



I've been thinking along the lines of a 20mm spacer to be on the safe side? That way I can run 225/40/18s like I had originally wanted. According to what you say that might keep my steering geometry in fairly good shape then?

Are you and Dale selling spacers? Or should I just go for something like this...
http://cgi.ebay.com/ebaymotors/H-R-Spac ... enameZWD1V

I'm thinking I'll have to put in longer studs too . There won't be anything sticking out of the lug with a 20mm spacer in there. What's the best place for studs?

Read northshorebrick's post in Showroom on T'Bricks. He just got a set of 15mm spacers from me and has pictures of the studs you'll need. They have to be welded in though...

I can still get spacers made. With the US dollar taking a nosedive, I've stopped promoting them as much as I did. Straight 15mm spacers aren't all that pricey. Those Ferrari pieces will likely have the wrong hub-centric ring size...

No, I said that 7mm would keep your geometry in good shape. 20mm certainly would not. But to be sure, you've got to check out the offset of the wheels that came with the car and compare them to the offset of the wheels you're trying to fit. The difference between the offsets is the "ideal" amount of spacer you'd like.

In reality, a taller tire requires a slight bit less offset, though a low profile tire for a bigger wheel isn't necessarily a taller tire.

If you want to go with 20mm spacers or thicker, Dale's will be of the adapter style unless you get longer studs. Kaplhenke sells longer studs, though I don't know if they're the 240 or 740 style. Even with a 7mm spacer, you probably won't need longer studs to bolt them on but if you are planning on stressing the studs at all, you might want longer ones for more thread contact. We've been using the ARP Ford 3" long stud for the 240 cars and welding them in, but I'm not sure how that translates to the later cars. I plan on finding out.

Ok.. back with some results

The 15" wheels on the car have 15x43 stamped on the back.. i'm assuming that means their offset is 43mm?

My 18x8 R6s have 45 ET stamped on the back.. I guess that makes my measuing of 45mm correct?

The wheels I tried fitting (17" pegs with 235/40s) have 17x46 stamped on the rear.. they were close to fitting, probably 10mm and they would clear for sure.

From what you say Matt a 2mm spacer would be best.. but obviously that probably won't be enough. I ordered 225/40/18s this morning so I'll need to fit those. I'm thinking a 15mm spacer should be enough now to get me by. The 235s on my 17" rims stick out 10mm past the rims inner edge.. so i'll cross my fingers on 225s not sticking out so far.. giving me a bit more clearance. All depends on the rubber though.

The poi is running 18x8 Ronal's with an offset of 35ET. He clears 225/40/18s, so I should really be ok with a 15mm spacer I hope (talking out loud here).

A 15x6 ET43 wheel has 4.69" backspacing (distance from the rear of the wheel to the mounting surface). A 18x8 ET45 wheel has 5.77" backspacing.

Assuming the strut tube has 12* steering axis inclination, the strut "moves away" from the wheel rim by .312" when comparing the 18" wheel to the 15" wheel.

Therefore, the back of your 18x8 should be about 3/4" closer to the strut tube than the 15" wheel is.

^^ all of that is pretty much pointless ^^

I'm going to assume your stock tire is a 195/65x15, and the rolling radius of that is about 12.5". The 225/40x17 rolling radius is fractionally larger, by about .050" or 1.27mm. That means you require an offset of (SIN12)1.27 = .264mm less than stock, so it's really not worth worrying about trying to change the offset from stock.

Therefore, to keep your steering geometry "stock", you're going to need a 2mm spacer. Also not worth worrying about, 'cause additional negative offset never hurt anyone.

The Pegs had tires that are an additional 10mm wider plus the tire is a bit closer to the strut due to the steering axis inclination, so I'm thinking that a 225/40x18 SHOULD fit...

But...

I wouldn't do it. Going hard around a corner will walk the tire around on the rim, and the tire could rub the inside of the strut. A 10mm spacer should be just enough to clear things up, and shouldn't mess with your geometry too badly (35 offset is still plenty for many RWD vehicles) The 10mm spacer would put you right at the same offset as Chris Wiita, too.

Matt.. you are hardcore. Just when you think there is a topic you can't get THAT technical with, you blow me away.

I'm going to put my trust in you.. I only want to run a 10mm spacer.. that way I might not need longer studs (there isn't alot of stud there to work with). But I'd much rather have it closer to the inside of the car vs sticking out.

Looking at a 10mm on a ruler and then looking at my clearance V

Makes me get down on my knees and hope it won't rub when cornerning. But.. like you said, chris has 35ETs on his 960 and he says it clears fine, so in theory I should be laughing.

Dale.. you'll be getting a PM shortly.