Aftemarket wheels and tires for roadracing
 

Which are the most lightweight wheels available on the market. There are some carbon fiber wheels from Dymag which weigh 14lbs but ive heard there are lighter wheels on the market?

As strange as this sounds, and for what it's worth, I'd recommend that you should not use weight as your primary criteria for rim selection. Imho, rim width is far more important, for an MKIV Toyota Supra Turbo (especially one that has been, or will soon be, upgraded). As you know, the Mkiv Supra Turbo, generally speaking, is a high-horsepower rwd vehicle, and the wheels that need to be on this type of vehicle need to be appropriate for that design. The widest rim that will fit on the oem Mkiv Supra body (jza80), without modification, and with the correct offset, is 11.5" wide. This will allow you to run 315s, which will actually have a chance of 'hooking up' all of that horsepower. If you go and (for example) put some skinny 9" wide rims on the car, you'll just sit there and spin, even at modest 'bpu' horsepower levels. In other words, lighter rims can make you slower (not faster) if they're an inappropriate width. Now, the trouble is that if you limit your wheel/rim brand/model selections to those you can get in an 11.5" width, you'll find it to be somewhat limited. A few of the brands I'm aware of that do come in that width are Fikse, Forgeline, Kinesis, CCW, and HRE. Although I personally have no experience with "Dymag" carbon-fiber rims, it's probably unlikely that they come in an 11.5" width...

Of course, after you do find a few choices for 11.5" width rims, with the correct offsets for the jza80, and rims strong enough for your application, weight can & should be one of the criteria that you use to select among them. :) Just mho fwiw, and ymmv...

thanx but i know the thing about width and traction and how skinny tires can make you slow but i was just wonderin what were the most lightweigt rims

Fwiw, I've heard that magnesium wheels are among the lightest, although generally not ideal for street use. Apparently the magnesium alloy, although very light, also tends to be brittle and will (for example) break/crack rather than bend if you hit a pothole too hard.
http://www.buywheelstoday.com/images_products/1279.jpg

Unfortunately, I doubt that these Enkei magnesium rims (or any ultra-light magnesium rims) are available in the correct width/offset combo for the jza80 chassis.

Update: I've heard that Forgeline and iForged also have ultralightweight magnesium rims. Since I know Forgeline does make an 11.5" wide rim, this might be an optimal choice for overall performance (if their magnesium alloy rim is available in that width).

Massive can of worms here, but from what I've been told and learnt over the last few years is wide rims and wide tyres do not guarantee the power getting put down on the road

The car has got to stick close to stock offsets, widths and similar rolling radius' as possible for optimum handling

Simply the R&D of Toyota can't be matched for this car and chasis, regardless of power output, obviously there will be slight le-way where you may change one aspect which will in turn affect another suspension wise - but it would be that small that you would barely notice a difference to your track times or your feel

Slapping 11.5inch wheels - guaranteeing a 315minimum fitament is not the way you want to go if your looking to keep the stock handling - which tweaked properly is very very good

In Drag cases its completely different - go as wide as you can with a very soft spring rate rear and you will knock seconds off your 1/4mile but street driving will not be anything like the optimum with a setup like that

I used to want as wide a wheels as poss - I have now went from 19-18's to try to stick with stock offsets and RR's they car feels much more planted now and I get more grip even with a narrower tyre

The minimum tyre width b.t.w will be stock - 255 iirc - best go with stock U.S wheel width 9.5inch and a 265 or 275tyre

With a good setup Lexus GS300 Sport Rims will do also as they have a stock offset and come in anything up to a 10.5inch wheel, however the suspension will need setup for optimum handling and grip especially the wider you go

On the front you want to keep it staggered - 8.5inch wide wheel for optimum turn in anything wider you begin to tramline, theres pretty much no benefit to running wider on the front on the sup

Check out the car Bible its a very interesting read and something you dont want to believe at first - especially regarding contact patch - it defies rational logic Car maintenance : Everything you need to know about wheels and tyres.

And to answer the initial question - stick with forged rims as you can have a very light cast wheel but it could break pretty easily, Volk RE30's are only 6.8Kg's a rim (18inch):yum:

With stock-width rear tires (255s) on an APU Mkiv Supra Turbo (eg. 750rwhp+), the puppy will just spin/slide...you'll have almost zero control in the rear when boost hits. Please note that I actually agree with you, IF (and only if) you keep your Mkiv TT bone-stock, then the oem rims & offsets are ideal. But if you reengineer the driveline, you also have to reengineer other parts of car, like the rim widths (along with the alignment and suspension to match, of course). This is speaking from hard-learned evidence and the twisted scraps of metal that once-were beautiful Mkivs. Of course, the choice and the freedom to experiment is yours. Alternatively, if you want to go with what has been proven to work in a 750rwhp+ Mkiv, get some 11.5" width rims in the rear, with a tall profile (eg. 35s or 40s) tire, preferrably race rubber (assuming dry conditions), proportionally wide front rims&tires to match, and watch it grip and handle (on a roadrace course - not a dragstrip) after the upgrades. Don't and ... well let's just hope your car insurance AND your life insurance policies are both up to date.

Your post flies in the face of almost all roadrace modifications that are done, and wider tires do have more lateral grip for a given vertical load. For example, most modified Vettes and Vipers all run 335s all the way around. Porsches with flared fenders to accommodate extremely wide rubber is commonplace on roadrace tracks. Agreed oem handling is good, but my personal experience says wider is a LOT better. Despite all of this, I really do welcome you to prove otherwise. Put a 750rwhp+ Mkiv on the skidpad with oem rims&tires and g-meter, and post the results here. Then slap some 10s&275s up front and some 11.5s&315s in the rear, with proportionally similar sidewalls (i.e. don't put some super-low profile rubber on the rear), same brand/model/rating of the rubber too, and re-test. My money's on the retest with wider rims giving you a much higher G rating.

Here's a quote that might help:
"...when you look at lateral grip (side force) other factors start to matter. The tyre develops side force because of the slip angle between the tyre and the road. This slip angle means the tread is being pulled sideways by the road surface. At the front of the contact patch the deflection is relatively small. As you move back along the contact patch the deflection increases steadily. At some point, the sideways forces in the tyre exceed the friction between the tread and the road and the tread starts to slip relative to the road. When the tread is slipping like this it produces less grip on the road. Now imagine increasing the slip angle and imagine what effect this has on the side force. As the slip angle increases the sideways deflection builds up quicker so the front of the contact patch works harder. But more and more of the back of the contact patch is sliding and losing grip. At some point you reach a maximum point where more slip angle means less side force because you are losing more grip at the rear of the contact patch that you are gaining at the front. This is often referred to as 'breaking away' where you ask the tyre for more grip and end up getting less.

The longer the contact patch is, the more gradually this break away occurs. If you shorten the contact patch, the break away occurs more abruptly but you get more absolute grip at the peak. This is because there is less variation in sideways distortion between the front and back of the contact patch, more of the contact patch reaches maximum grip and starts to slide at the same point. Having a shorter contact patch also means you get less self-aligning torque so there is less feedback through the steering about how close the tyres are to breaking away.

When you fit wider tyres, what you're doing is making the contact patch wider and shorter for the same tyre pressure. This means you get a more abrupt breakaway but more grip right on the limit. The disadvantage is more expensive tyres, more tramlining and steering kickback, more wind and rolling resistance and noise, less grip in slippery conditions, a more abrupt breakaway to catch out the unwary driver and less warning through the steering about how close the tyres are to breaking away. "

Lastly, consider a couple of things:
1) The contact patch actually isn't the same with narrow vs. wide, since the steel belts in the radial change the shape of the contact patch.
2) Wider rims & tires means a wider wheelbase...which in turn adds noticeably to the lateral stability (you can actually feel a difference, through the first hard corner you turn after running wider rims).

Again, imho, wider is always better.

:)

Ok I was hoping I was wrong in all honesty - my post above is what my thinking has been directed to after a few years as logical thinking has always been wider tyres on wider, approriate wheels = more grip

I'm the first to admit, I have knowledge in almost all aspects of the car apart from suspension and handling - I just havent done much research on it as I have been busy speccing my engine,fueling,management e.t.c

I have always wondered how/why in the UK people run close to stock widths whereas in the U.S you guys seem to run 10s upfront and 11.5's rear

We have pretty much two supras in the UK that run Timeattack, they run 10.5up rear and 9 at the front, they dont particularly run fast times - well in comparison to the 4wheel drives and the ubber responsive GT2's, their my benchmark

So I'm currently speccing my wheel sizes and offsets to suit my Brembo BBK's front and rear, you recommend 10 at the front and 11.5rear on a stock body?

I will be running a super responsive 600bhp and around 550ft/lb of torque with speed dependant boost so I can get the grip down

Wont the wider tyres in the front give me a less responsive turn in - you have to bare in mind that the tracks in the UK are like 100th of the size of the ones in the U.S - i.e my local track I should get round in 58secs, there are a few bigger ones but not longer than 3mins e.t.c however I do intend to go to the Nurburgring this autumn

Yes. Be sure to check the rim diameter you need to clear the brakes. Next, check the sizes of the tires that you plan to purchase and use. You may not be able to get near-optimal 275s or 285s in the front, and 315s in the rear. Maybe you'll end up with 265s up front, and 295s or 305s in the rear instead. Also have one or two back-up tire brands/models in case the company stops producing your first choice. Lastly, get the rim widths to match the rubber you'll be running. When you come close to your decision, please feel free to post here, and we'll provide feedback.

Low profile, wide front tires will give you a MUCH more responsive turn-in. You'll be shocked when you switch from oem 235s to 275s or so up front. Of course, it'll be a bit harder on your power steering, so be sure to follow proper maintenance, and use good fluid (eg Redline Power Steering Fluid).

Hypothetically, if you widened the back tires, and kept the oem front tires the same width, it'd push in the corners (i.e. turn-in would be less responsive). That's why you have to upgrade both the front and the back widths simultaneously and proportionally.

Please post any follow-up questions you have...and good luck with it - please keep us informed!

I'm running ccw classic 18X10F and 18X11.5R on mine and they are pretty light specially comparing them to stock 17" factory chrome wheels.

rims
 

I'm looking for a new set of rims because my older work rims have a offset of +47 on the front which wont probably clear a big brake upgrade package, so does anyone here have any sugestions on what offset is possible for larger calipers such as the brembo or stop tech brakes?

What is the diameter of the rims you're currently running? If they're 18" or more, they'll very likely clear most big brake packages.

Also note that you could shim the rim if nececessary - hub-centric shims come in various thicknesses and are a viable solution. For example, I had my oem rear rims widened from 9.5" to 11.5" and I ran one-inch thick shims, bolted to the hub. Each shim came with its own studs, which the wheel bolted on to (the holes in the shim for the oem studs were in between the shim's studs).
http://www.mkiv.com/techarticles/par...ned/index.html

rims
 

Currently I have 18x9 front and 18x10 rear. my supra is a J-spec TT , which comes with the normaly aspirated brake set up. Theres barely any room between the brake calipers and front rims.

Im thinking of installing the north american style TT Supra brakes, not sure if its a good idea or should I just buy brembos or Stop techs?

one thing i havent seen being considered in this thread, is inertial weight.

remember, his application is road racing. so just weight and width alone are not the only factors.

a wheel that has more hub-centric weight, could weigh more than another wheel, yet still get up to speed (so to speak) faster.

vice versa, a wheel that has most of its weight toward the drop center and rim lip, will take more effort to get rolling, but be easier to control and keep momentum up in an application like road racing, where he will almost be constantly moving.

and depending on restrictions for his races, he may not need an intensely wide wheel if he gets the proper tires. applying the power to the ground is imperative on tire selection. you can have 335mm tires, and still not grip or handle for beans. while you can have a 275-295 width tire that would give you superior handling.

just some thoughts. everything else thats been brought up was farely spot on.

in my research, fikse wheels has a great selection of light, wider and weight balance. there are others, but like i said, my research lead me to fikse.

GL!:bigthumb:

I fully agree with pwpanas serves on point with the info.I am currently deciding to go with 9 x 19 with a +43 offset front wrapped in 265/35/and rear 11.5 x19 with +44 offset with 305/40/19 problem is I don't know how this will look nor how much body modifications I am gonna face.Any help?

I can't answer to the offsets without going thorough some calcs. I'd recommend you have the company or person you purchased the rims from to guarantee fitment...especially proper clearance from the suspension (but not too much!). The wheel/tire should actually touch on the oem suspension when the car is up on jackstands and the wheels are hanging down as low as possible. With coilovers, there is still a tiny bit of clearance when the wheels are hanging at their lowest point.

However, I can tell you about the body modifications. Actually there is only one modification: Just get a reciprocating saw or a jigsaw and cut the rear fender inner lips. Tape it off beforehand so the paint is protected. Go over it afterwards with a grinder to ensure no sharp edges. Spray paint it afterwards so it doesn't rust. Done. I've done it dozens of times on Mkiv Supras, and the fender is no weaker than before...and you can barely tell its been modified unless you know exactly what you're looking for. Done right, and with the right offsets (I'd recommend +50mm for 11.5" width rims) 315mm width rubber fits perfectly with no rubbing at all (assuming stock-ride height suspension).

A few more details on the cutting process itself:


Basically you will cut a smooth line from the body joint in front of the rear tire to the back of the rear tire, over the top (of course). You want to trim away as much as possible (really!) - there shouldn't be more than 1/8" left of the lip on the extreme inside (when you curl your fingers around and feel downwards from the top). Across the bottom edge will be closer to 1/4" or so. Of course, there is no change at all to the outer (painted) fender. This nearly complete lip removal maximizes the clearance for the tire as it moves up and down with the suspension.

• From the starting point at the body joint, do a relatively sharp curve to that max lip cut width
• Follow that max lip cut width *straight*, up and over all the way to the back joint
• do a relatively sharp curve back out to the opposite body joint
• It helps to draw a line on the tape that you used to protect the paint (eg. with a sharpie)
• Be sure to angle the reciprocating saw's blade slightly so the tip of the blade doesn't hammer into the inner fender (at a point beyond the lip) and keep that angle consistent throughout the cut.
• Again, be sure to go over it with a grinder to round off the sharp edges, and then primer+paint afterwards.
• Take a look at the attached pic for reference.

Got it? If not, please post or PM me with any questions.

Oh, here's what not to do:

• Don't try to"roll" the fender lip. The fender lip much too stiff and will distort the fender if you try (yes, even with an expensive fender rolling tool).
• Also, don't try to cut the lip with any sort of grinding wheel or dremel. This puts too much heat into the fender and will (likely) discolor the paint. Even with a reciprocating saw the fender will get quite hot - if you have a buddy helping you, you can keep the paint cool with wet rags while you cut with the jigsaw or reciprocating saw.

hi pwpanas, my set up for my mk4 tt 6 spd.
front: 18x8.5 + 45 ( 245x40x18 )
rear| 18x10.0 + 50 ( 295x35x18 )
it that good? or bad?
thnx.

I'm sorry to say that I don't really consider that much of an upgrade over the oem rims. The oem rims are 8" wide in front and 9.5" wide in the rear. If you're going to spend the $$$ on aftermarket rims, why not go with something substantially bigger? I consider 9.5" wide in front and 11.5" wide in the rear to be a bare minimum. With fender flares (eg. Veilside) you can run even wider rims.

What is your horsepower spec? If you're still running the oem 320rwhp with the oem twin turbos (i.e. not BPU, etc.), then perhaps those rims really are okay...