Rota Grid 17x9.5 for racing
01-30-15, 11:11 PM
#1
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Rota Grid 17x9.5 for racing
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.
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.
01-31-15, 03:21 PM
#3
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.
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.
01-31-15, 04:05 PM
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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.
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.
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.
02-01-15, 10:55 AM
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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?
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?
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02-02-15, 03:59 PM
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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
https://www.rx7club.com/suspension-w.../#post10574842
Part Two: What kind of space is there between the suspension and outer fender to put wheels in?
Inner clearance limits (AKA maximum back-spacing approximations) Again, tire size will affect these limits, and these figures assume that overall tire width does not exceed rim width by more than 1”or 25mm, so 225 on an 8” wheel, 255 on a 9” wheel, 275 on a 10” wheel, etc. )
-150mm up front on aftermarket suspension, closer to 140mm on stock suspension. I would not personally go over 140mm – 5.5” back-spacing. For the rears, a little more room to play at around ~155mm inner clearance on stock suspension, or 5.9” back-spacing. Possibly more on aftermarket coilovers.
Remember, as ReTed says “it's easier to roll your fenders rather than take the risk of hitting something on the inside.” So err to the side of caution for inner clearance, especially noting that not all tires are created equally.
...
Inner clearance limits (AKA maximum back-spacing approximations) Again, tire size will affect these limits, and these figures assume that overall tire width does not exceed rim width by more than 1”or 25mm, so 225 on an 8” wheel, 255 on a 9” wheel, 275 on a 10” wheel, etc. )
-150mm up front on aftermarket suspension, closer to 140mm on stock suspension. I would not personally go over 140mm – 5.5” back-spacing. For the rears, a little more room to play at around ~155mm inner clearance on stock suspension, or 5.9” back-spacing. Possibly more on aftermarket coilovers.
Remember, as ReTed says “it's easier to roll your fenders rather than take the risk of hitting something on the inside.” So err to the side of caution for inner clearance, especially noting that not all tires are created equally.
...
Last edited by driven-daily; 02-02-15 at 04:00 PM. Reason: cut out excess, click the link if you want to read it all.
02-03-15, 10:41 AM
#9
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.
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.
02-03-15, 10:53 AM
#10
Triangles and Cats
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.
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.
02-03-15, 11:37 AM
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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.
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.
02-03-15, 11:46 AM
#12
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.
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.
02-03-15, 11:49 AM
#13
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.
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.
02-03-15, 01:56 PM
#14
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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.
02-03-15, 02:26 PM
#15
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
02-03-15, 02:38 PM
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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
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.
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