Grizzly

Ok, i've been doing some searching but can't seem to find what i'm looking for.

Basicly what i would like to know is what is the Lowest + offset you can use with 18" rims (8" front and 9" rear) and not catch the arches on a stock Body car?

I have found a few Threads where people have been using +29 (17"x 8" & 225 tyres all round) without any problems (well they said "with no Body mods") so would that mean a pair of 18x8's with 30-32 offsets would'nt catch the lips? Going the other way i've not seen any 18" Offsets past + 45 without Issues (not much space between Tyre/Rim and Strut)

Then the rears, well i was told not to go lower than + 36 (does this sound about right on an 19x9?) would making them any lower catch the Arches? (ie. could'nt run +32's in 9")

Thing is i'm going to be fitting Big brakes so i need as much space inside the rim as poss, so i'm going to get the offsets as tight as i can then roll the Lips too be on the safe side, but as always i can't try the rims on before i buy so its a bit of a risk.

Grizzly

O yeh its proberly a good idea to say my car has been droped about 30mm too.

TehMonkay

iTrader: (-1)

It would also help to know if you have an fc, fb or fd as well.

rynberg

We have a stickied minimum offset calculator at the top of the forum. The spreadsheet assumes stock ride height so you will want to be more conservative with a lowered car.

Grizzly

*****!! I used to have a pic of my FD on my Avatar (seems to have vanished). But yep FD.

I'll have a look at the offset Calculator.

Cheers

Grizzly

rynberg, Do i need Exel to open it? i've just done a Reinstall and i'm just putting back the stuff i need (i have a habbit of filling my Drive full of Crap)

This is the Thread you mean? https://www.rx7club.com/suspension-wheels-tires-brakes-20/fd-wheel-tire-sizing-416251/

rynberg

You can use Excel or a free viewer. You do not need low offsets to run big aftermarket brakes, brake clearance is determined by wheel diameter and spoke design more so than offset.

The offsets you are talking about in your first post are too low, stick in the +40 to +50 range, depending on wheel width.

Grizzly

Ok, just put Adobe on and it opens fine now.

I'm a little confused, it says the ideal offset to keep a 1/4" gap between the fender and the rim in 18" (8" front) is +31 and for the same 1/4 gap on the rear (9" rim) it says its also +31 it also says this at the bottom "This number is the clearance between the tire and the fender. Offsets have
been calculated to maintain about 1/4" clearance so that rolling fenders should
not be necessary unless the car is excessively lowered.
If a larger offset is selected, it may be necessary to roll the fender lip to avoid
rubbing or to use flares for additional clearance." So am i correct in thinking they are using the Lip to set the Fender - Tyre gap?

I've gone off the Fist post on this thread https://www.rx7club.com/showthread.php?t=416251

AntiVenom7

is there a particular set of wheels you want to fit? generally if you wanna run an 8-8.5 in front you should be looking a greater +40 offsets. I have a +43 with an 8.5 wheel and 255 tires. only rubs under extreme conditions (like ~90* uphill turns, or large dips in the road, where the car bottoms)

run +45 on the back with 9.5 and 275s, with no rub ever.

running a narrower tire i guess you could get away with less, but not by much. with a lowered car i would suggest staying in the 40ish range, unless you are gonna run super narrow tires.

Grizzly

Well i was planning on running 225/40/18 fronts on 8" rims and 255/35/18 rears on 9" rims.

I don't have anything in mind, i'm just trying to find out what would be the best offsets and what are the limits (highest and lowest) i can fit and not have any Issues, mainly so i don't end up buying something that won't fit.

I do have another Issue that could be a factor, i will be fitting a big brake Kit in the next few months which will include a set of aprox 320mm rear Disks and 4 pot calipers so what ever rims i use they have to have good clearance (which is why i started looking at low + offsets)

rynberg

You need to be looking at wheels that have higher offsets like I said above. The spreadsheet is based on fender lip clearance, not what is ideal for handling performance. I would also go with wider wheels, what's the point of changing wheels to stay so skinny?

For good brake clearance up front, you will want to look at wheels with spokes that curve out from the front of the hub before coming back to the rim face. I doubt you'll have any issues with rear clearance but almost no one has ever run a 4-piston large rear disk like that on an FD (because there's no point).

Grizzly

I don't know about no point, i think the stock FD brakes are realy poor on the Track (go off realy quick when your going for it) i think you don't see them mainly because its rare to see a 4 pot with a Hand brake.

Going back to rims etc, I thought about going wider but living in the UK we drive in the rain quite alot so having a smaller tyre Footprint realy helps (sounds daft i know but wide tyres tend to Aquaplane alot easyer) So what it comes down to is i will be using one set for the Road and a less prity set with Slicks or Int's for Trackdays (if i go this way i can use my Stock rims with some Semi slicks on for playing well untill i do the brakes )

rynberg

Running 99+ rears with good pads should be about as much heat capacity as anyone would need....

I don't think your fears about hydroplaning are that justified in the real world. Just slow down a little if it really comes to that. Even when I drove the car regularly in the rain, I never compromised dry grip for wet performance.

Grizzly

nice, i work for a Body shop and the no1 cause of Crashes here is Standing water on roads, Unless you have some real good Tyres going on you hit it and your just there for the Ride no matter if your doing 20 or 120 (just means you hit harder). I bet you don't get Flash floods in the middle of summer months? or 6 foot floods?(last week)

I think the Pic below is just realy funny The Royal's always have to see damage for them selfs (Muppets)

Grizzly

I did look into these but i got my Big rear brakes for very simalar money to a set of RZ 99 spec Rears New. Plus a Good mate had a Spirit and i drove it two or three times and they felt just the same as Stock??

rynberg

It doesn't matter what tires you have on the car if you are hitting standing water....and here's a hint, if it's rained that much, don't drive your FD!

I think you need to reread the part about good pads in my statement. What brake setup did you get? You can't just bolt up any old setup you know.

Grizzly

I think this is getting way of track.

Lets just say for arguments sake i want to fit 8" ft and 9" rear 225/40/18 and 255/35/18 what is the Lowest + Offset i can get away with without Rolling the Fenders?

According to the Link every one keeps telling me to look at its +31, but your telling me +40's?

My brake set up is massive (not nearly like stock) it has a new Twin Cylinder Master and does not use a Servo (no power assist) its a propper Track set up with 6 pot fronts and 4 pot rears, i have done this because from experiance of track days etc the stock brakes leave alot to be dresired when pushed and when i looked into it the Cost between 99rz brakes and my 320mm monster brakes where withing a £200 diffrence so i went with the better for me.

Grizzly

Thats just a Dumb thing to say, In the UK it rains....oviosly if its flooded nothing drives. You soon find out there is a Sweet spot in the tyre range where the Dry grip and wet grip ballance out, also there is this thing where if you fit 320/30/18 tyres to a car that weighs 700kg you may get good grip in the Dry do you get better grip than decent 225's? i will put money down that that the first time you see water you will end up facing the wrong way. Its all about the Presure the Tyre Foot print puts down on the road to push the Water out of the way if the tyre is wide you will loose the pressure and the Aquaplane effect come into play. I have not got into the Unsprung weight yet.

rynberg

Since you are lowered, I would not go below a +35. Your intentions are confusing to me though, because you are mixing track setup with practical rain weather setup = does not compute.

If you want to perform well at the track, you should be looking at wider wheels/tires with higher offsets for clearance and to maintain the stock scrub radius/geometry.

It's not a dumb thing to say....why drive the FD in the rain if you don't have to. Get another car for that kind of driving.

Grizzly

so if i start from stock and look for a rim between +50 and +35 it will fit ok? Does that go for the Back's too? (being 9") i have read that the rears sit in about 12mm more than the Fronts?

Yep i think i don't explaine myself very well, at the moment i will be using my Stock rims for Trackdays etc but there is a Good chance my Stock wheels won't fit over my shinny new brakes, so whilst i'm saving for a set of Track rims i will be using my Every day rims for trackdays etc (which i don't really like doing because they will be more for show and i'd like to say in the 17" range for the Track wheels, possably will go for 9" all round and Tyre cost won't be as big an Issue)

rynberg

No way will stock rims fit over larger brakes like that.

You can generally get away with an offset about 7-8mm less at the rear, from a fitment perspective. It would be good to keep the offset consistent though.

Grizzly

Thats what i thought (the new brakes look alot bigger in the Box), but i've been told by people who already run this sort of Big brake kit that i may have issues with the shape of the rim as opposed to the Offset when i go up to 17" or 18", but we'll see.

rynberg

Isn't that what I said above? Lots of people run +50 offset wheels with big brakes just fine....it is the shape/depth of the spokes that is more important than offset.

chemicool

iTrader: (1)

Hey is that your car? I like those rims. WHat kind are thos and sizes? Also, where did you get that scoop for the side? Looks good

Grizzly

I think thats where it went all confused, I was thinking of having two sets and price of tyres was in mind , i think you thought i ment these would be my No1 set and be bought for Track days first and road second, But i'm looking for some nice looking rims and was thinking of checking the Second hand market and wanted to know what was the Max Tolarance that would fit. The Track wheels are going to be a Diffrent story There going to be more along the lines of what is the lightest Rim i can get in the size and Offset that will best suit.

chemicool, Thats not my Car so i could'nt say exactly what it has had done but by i think there Masdaspeed side skirts that have been blended in? (could be wrong??)