I'm trying to get as much street-legal rubber as I can for my race class, and it looks like my best tire options are in 275-40R17, so I've been hunting around for reasonably sized wheels for those tires. The wheels aren't beautifully light or incredibly strong, but I really need all the grip I can possibly get here and they're within the budget for the year.

With an aftermarket coilover conversion, can anyone confirm how much backspacing I can get away with before interference with the spring? The wheels I'm currently looking at are:

17x9.5
+12mm offset, which comes out to around 4.25" of backspacing
This is an 87 with 4x114.3 hubs, which probably doesn't make a difference ... but I'm not familiar enough with the platform yet, so I can't be 100%.

I don't have any problem with making some fender flares or using bolt-on overfenders, and clearancing the sheet metal wheelwells doesn't scare me at all. I'm not willing to move suspension pickup points yet though, so I'm looking for a bit of feedback from the community here.

 

Correction: 5.25" backspacing. Math is hard, it turns out.

 

FC3S Pro v2.0: Mods - Rims

Guide I typically used.

I did have 17x10 with +20 offset and ran 275/40/17 Nitto 555R Dr's on them. Did have to roll the fenders. According to Ted's site, you may have to run overfenders, roll, pull, or something of the like. I did fit the same size Mickey Thompsons, but had a little rubbing (tire height may change brand to brand).

I remember your post on these wheels before. I figure you like the style. Why not find rims in a 10" wheel or a 9" wheel that has better options for offsets for our cars?

Otherwise, prepare to do some extra work to make them fit. Hopefully someone that has ran less of an offset of a wheel can chime in.

 

That guide was helpful, but didn't lay out how much backspacing is available. I'm absolutely all ears for other sizes, as long as they're 4x114.3, reasonably priced, and not too heavy. The Grids were the closest I could find, but that certainly doesn't mean they're the only viable option.

I assume the rubbing you had was just the tire against sheetmetal, and not suspension components? I couldn't be less concerned about fender or wheelwell clearance, that's a very easy fix. Suspension components are challenging to move without ruining suspension geometry.

 

Racing replica wheels is risky business, be cautious.

 

May I ask why you need such wide rubber? I can't imagine you putting down much power while still being 4 lug...

 

Racing is risky business, it's a good idea to be cautious about every purchase. Show me statistical evidence that Rotas fail more frequently than more expensive wheels, and I'll modify my budget. Otherwise, they have a good reputation in general, and would appear to be a great value for my needs.

This has nothing to do with power, I could be extremely optimistic and estimate 175whp on this car, but I think 140-150 is more reasonable. This is definitely a momentum car, and I need all the cornering grip I can get.

As an extra benefit, these wheels (lug pattern, offset) would also fit on my Datsun project (325ft/lbs at the wheels). I've never seen 4lug hubs fail because of power, so I'm curious to know why that's a defining point for you. Do the 4lug rx7's have weaker hubs or spindles than the 5lug versions?

 

It looks like I found my answer after a bit more digging. It was right in one of the many FAQs (~5.5" of backspacing as the maximum in the front). These wheels are under 4.5" of backspacing, so there will be plenty of room to fit them in. I'll almost certainly need to roll the fenders at least, or overfenders/flares could be required. The 'frontspacing' is closer to 5.25", and while I haven't measured from the hub to the outside, I can't imagine doing that without having interference issues.

https://www.rx7club.com/suspension-w.../#post10574842

 

Yes you are gonna need over fenders.

To fit the 17x9.5 wheels under the front fenders the offset needs to be in the +26 range. The wheels you are looking at will be half an inch further outboard than the wheels below. These are 17x9.5 +38 with a 5/8 inch spacer (15mm). You'll have a big problem in the rear too. You need something in the 17x9.5 +35 to +38 area to let the fenders clear the tires. All this assumes you want to run normal sized tires and not stretch some small tires on these wheels.

 

What are your wheel and camber specs again?

 

Thanks very much, this is a huge help. In my mind, the only reason to run wider wheels is to run wider tires. It sounds like I may be able to squeeze by with just a fender roll. I need to make sure I can afford suspension and wide wheels/tires (275-series tires get expensive, I'm seeing) this season, but this looks promising at the moment.

 

No problem. You can run 255s all around on 9 inch wheels pretty easily with a track oriented alignment and the correct offset wheels. the 255s work pretty well on the 9s. With 9.5 inch wheels the offset is very critical, and the wheels will rub the swaybar under full lock if you fit them under the fenders. There is not a whole lot you can to about that.

In order to fit that wide of a wheel and tire under the fender you will NEED coilovers. I don't know if you will be able to get the offset you need to make it work with 4 on 4.5" bolt pattern wheels. The low offsets those typically come in make it a challenge.

I am planning a setup now and believe I can fit a 275 tire on a 17X9.5 wheel under the stock fenders. I am going to try it when I wear out my current 255 NT01s.

Also, with the 9.5 +38 with 5/8 spacer here is the strut clearance. There is some room to work with.

 

At this moment 255/40/17 all around on 17X9+24 wheels.

Front camber is -2.9 degrees, rear camber is -1.5 or so. Rolled fenders in front, rolled and slightly pulled rear fenders.

The wheels are as far out as I can can push them. The rears still rub occasionally.

 

we've been running ROTA's on the race track for more than 10 years now, and we've never had any trouble with the wheels, unless we hit stuff, which happens. we're actually running grids now, i think, they aren't the lightest things in the world, but other than that they do fine

 

I'm also currently running Rotas (P45R3s) and they're fine... and actually surprisingly light for their size.

 

Hitting stuff on a track is going to cause problems with any wheel. I've seen the more publicized hub failures for Rota wheels, but I've seen the same kind of anecdotal evidence that other brands fail as well. This is all the reinforcement I need to confirm these.

The 17x9's with 255's looks like a pretty solid setup. I have some experience doing work like this (I wasn't involved in this car in any way, though) on previous cars, which seems like it'd be ideal for the FC:


As long as all the planning is done ahead of time, this is a relaxed-pace weekend project to get all 4 corners done. If I could get a lower (or even negative offset), I wouldn't have to worry about clearance, just bump steer.