Will 18x9 fit on the front?
 

Looking to go to wider wheels on the Boxster racing car for next season and working out what I can fit.

I will be installing the rear fender flare from AIR and hope to get space for 18x11 in the rear, but how wide can I go in the front with the factory front fenders - will 18x9 fit?

Yes, A 265 tire will fit on a 9" rim in front with careful attention to your offset. A 245 on a 8.5 wheel might be faster though. It depends on the tracks you run and your RWHP.

Interesting. I am currently running 18x8.5 and 18x10 with Michelin Pilot Sport Cup 225/40 & 265/35.

The car is a dedicated racing car 2001 Boxster S which has been remapped. I will have to dyno the car again, but hope to be close to 300BHP. I am also running with a 2.5 5 speed gearbox with an LSD for better gearing.

Like I said above, I will be putting on the AIR Boxster rear fender flares which gives an extra 2" so could maybe even go up to a 18X11.5 or 18x12 rear wheel. I would have liked to get the current 18x10 that I am running in the rear to fit in the front as then I will only need to get new rear wheels ;)

Unless you are running a 3.6L or turbo you are probably nowhere near 300rwhp. Get it on a true dyno so you know what you are working with. Oversized wheels can work well in AX but slow you down on large tracks. Too much unsprung, rotational weight and straight line rolling resistance. The fastest Boxsters in SoCal are running 245/275 tires.

+1 on that !

Sorry, I was not referring to rwhp, I was talking about at the flywheel. The car will be going onto a dyno before the start of next season (we need to supply Hp results every three years, and mine is due for next season), so I will know for sure what the engine power is then.

I know that it is possible to go to wide, so appreciate the input.

Most of the racing tracks that we dire over here are not large fast ones like you have in the US. Ahvenisto is a good example of a track in Finland - Ahvenisto Race Circuit - Wikipedia, the free encyclopedia
"The Ahvenisto Race Circuit (Finnish: Ahveniston moottorirata) is a motorsport race track located in Hämeenlinna, Finland. The 3,040 metres (1.889 mi) long circuit is run clockwise. The track has an elevation change of 32 metres (105 ft), the home straight is 280 metres (0.2 mi) and the width varies from 9 metres (30 ft) to 17 metres (56 ft)."

http://upload.wikimedia.org/wikipedi...rirata.svg.png

I have had some on track contact this season, so the car will need body work done over the winter and I was going to use this as an opportunity to go wider. But based on what you are saying, maybe I would be better to stay with the wheel size I am already running with?

There are practical limits to running wider and everything is a tradeoff. We look at data a lot and we look at top finishers. What are they doing?

Here in SoCal we have tracks of every configuration, from tight technical 1.8 mile circuits to big sweeping 3rd/4th gear tracks, to 150mph+ super-speedways. I have run a lot with 255 tires up front during testing and rarely do I find a performance advantage. Never on a track with high speed straights above 120 mph. Top speed suffers in my car with 255s up front. With only 170 rwhp I don't think my car easily overcomes the added rolling resistance, windage, and rotational unsprung weight of the larger tires. Add 100rwhp (Cayman R or 3.6L motor) and we might get a different result because hp is king on a long, high speed straight.

So if you want to win your class, consider everything: running weight, RWHP, tire compound, track configuration, rotational weight, windage, rolling resistance, and then begin to make decisions about what your ideal contact patch will look like. Once you make some tire choices, go out and test them to see how well it is working, analyze, readjust. Now you are ready to win.

:cheers:

Off topic, but I'm glad to hear this works. I had been thinking about trying this myself for the lower final drive ratio.

I would be Really surprised if there is any speed advantage to be gained by going beyond the 8.5" wheels you are already running. Only a stopwatch will tell you but let me ask. Do you feel as if the car is under - tired as it stands? Also, what tires are you running and is there any restriction on what you are allowed to run?

Laurie

You are probably correct, and there will be no benefit in going wider than I already have.

Do I feel that the car is under-tired, not sure. I do feel like I could do with more grip at times, but that can also be altered with suspension and a better driver :)

There are no restrictions on tire make or size for us. I am running with Michelin Pilot Sport Cup. I was running with the Toyo R888 last year, but could not get used to them and find the MPSC much better.

I am currently running 1st in class and 2nd overall in the 2012 Porsche Sports Cup Scandinavia season here in Finland, and just looking for that extra advantage for next year and thought that maybe a bit more rubber on the track might help?

Are Hoosiers available where you are? If so they would certainly be quicker. Slicks (from any of the major makers) would be faster again. I'ld be looking there before thinking 1/2inch of extra wheel. R888s are **************** as all of us who drove them in SpecBox last year found out.

I think we can get Hoosiers from the US, not sure if they are available here in Finland. I know I said we are free on tiers, but that is not quite true. They must be EU approved road legal, and I am not sure if the Hoosier is approved for road use in EU?

Slicks could be run, but that will put me in a higher class with the GT3 Cup cars and will require changes to suspension and alignment settings.

I am for now happy in the class I am in. There is good competition and I am not winning every race I enter, so still a good fun race. But there are more 996 cars coming into the class and I am having problems keeping them behind me - they are faster, so any advantage I can get I want to take...

Yes, the 18x9 will fit on the front. That is what I'm running now with the 250 front slicks. You may able to roll the fenders and cram a 9.5" in there but you really don't need to at your power levels. I prefer a larger front for the better braking and longer lasting front tires during a race, but there is definitely a point of "too big".

http://i1089.photobucket.com/albums/...m/DSC_5649.jpg

Thank you Eric, we have also had the same discussion on the front wheel fitment on another forum ;)

But now that I know that it can fit, then question that is coming up here is if it is a good idea for me to go to a wider front and rear set-up or stay as I am - what do you think Eric?

For a 3.2L Boxster, I would want more than a 225/265 pair. A 245/275 would be nice and is available, or even a 255/285 with DOT tires. It does does depend a bit on the track you run, but I would always want more than a 225 DOT(or EU equivalent street rating) to get the most out of that car in the front. You are running almost Boxster spec sizes with another 100hp, and a bit more weight I believe. So I would expect the additional footprint could be put to good use.

Thank you for the recommendations Eric. My initial plan (and a way to try and keep cost down) was to try and move my current rear wheels to the front and then go 2" wider on the rear. This would give me 18x10 on the front and 18x12 or 18x11.5 on the rear.

Do you think this would be a good fit for my car or am I starting to go to wide?

Yes, the car is a 3.2 which has been remaped to get as much power from it as possible. It is also running with a 2.5L 5 speed box with a competition LSD to get better gearing and acceleration for the tracks that we have over here...

OK, so the car is now in the body shop getting the scars from the 2012 season removed, and the front and rear fenders getting widened. I will get an extra 1.5" - 2" on the front and an extra 2" - 2.5" on the rear. This I hope will give me more options on wheel size etc.

I run with Michelin Pilot Sport Cup, and looking at available size to fit a 18" wheel I am considering going for 295/30 - 18 at the rear and 265/35 - 18 on the front.

Initial thought is to get a 18x10 wheel on the front and an 18x12 on the rear, and this leaves me with a question - what offset do I require to make the wheels fit the Boxster?

He did not say 300RWHP, he said 300BHP, which is certainly attainable with a 3.2 motor, if not economical. Putting a 3.6 in a Boxster has to be at least a $10,000 undertaking unless your labor is free.

If things like emissions, efficiency and streetablity are of no concern, 300BHP should not be a huge undertaking for a 3.2, nor insanely expensive.

Regardless if it's WHP or BHP, that's way too much unsprung rotational mass to effectively improve performance on any level.

OK, so I need to go smaller - how about 265/35 on front and 295/30 in rear?

I don't have much experience when it comes to race/track applications. However, based on the size(s) of the wheels alone, one would have to think that you're adding a tremendous amount of unnecessary weight. Especially, considering the fact that it's unsprung rotational mass.

Kroggers you did well last year with what you have, DFIU!

Run the same wheels with 245/ 285/30 or 285/35.

285/30 is shorter than what you had= lower gearing or 285/35 is taller= taller gear.

Too much of anything is always too much! :cheers:

I have been back and forward on this so long now I am starting to go mad :D

Having calculated the cost to get new wheels etc, I have decided it will not not fit in my budget for the 2013 season (I still need to pay out for the body work etc as well).

So with some thought I am going to do something close to what you are suggesting. I will run next season with my current wheels which are 18 x 8 and 18 x 10 and widen the track with adapters - cheaper than getting new wheels etc.

If I run these wheels with 285/30 on the rear and 225/40 or 235/40 on the front, then that gives me a half way to where I am considering going and I can see if I need more corner traction for the following season or not :)

The issue with the front is that Michelin recommend that you do not go wider than the 225/40 on a 18 x 8 wheel. They say that at a push a 235/40 can be used.

It makes no sense why Michelin would say that a 235 tire is suboptimal on an 8 inch wheel. It will fit perfectly well without any concerns.

I fits fine but a wider wheel will stabilize the tread & sidewall.

I agree. But, Ive utilized both fitments with great success.

I would have thought that on a racing car you want the tread and sidewall as stable as possible in a turn?

I have the specifications from Michelin (in Swedish) and they state the following recommendations:

.- 225/40 R 18 wheel size 7,5/9
.- 235/40 R 18 wheel size 8/9,5
.- 265/35 R 18 wheel size 9/10,5
.- 285/30 R 18 wheel size 9,5/11
.- 295/30 R 18 wheel size 10/11,5

In the specifications they say to get best performance you should select a wheel in the middle, so a 285/30 would perform best on a 18x10 wheel.

So with my current 18x8 and 18x10 I could run 235/40 up front and 295/30 on the rear, but Michelin suggest this would not give best performance.

There may be an "optimal" tire/wheel width ratio, but most people can't afford to change wheels every time they want to test a new tire setup. A bit to either side won't cause any problems.

& this might be your best bet:

4 Fikse Mach 5 Cayman S spec wheels - Classifieds


:cheers:

Thank you for the link, did not know that the Cayman can fit 10 & 11x18 - do they have the same offset as the 2001 Boxster S?

Those are nice wheels, but by the time I have paid out for shipping to Finland and our nice import costs, it would probably cost more than having new wheels made to fit my car over here?

offset are close if not identical. Check out Fikse website, their wheels are much lighter & stronger than OEM wheels. Aren't there ways around import costs for used parts?

I have decided that I will have the wheels made to fit my car. At the moment I am talking to a company in UK to get the wheels made.

Unfortunately, import costs to Finland is the same for anything - new or used :(

The wheels from the company in the UK cost a bit more than the price on new Fikse wheels, but I save on shipping and import.

And here is what the new wheels are going to fill - collected her from the body shop Monday evening :)

http://986forum.com/forums/uploads01...1352882602.jpg


http://986forum.com/forums/uploads01...1352882642.jpg

I need some help. I found some wheels I want on this website, and want to put them on my 2002 boxster s. They are 20x9s front and back. I am running 18" stock wheels currently. Does anyone know if the 20x9s will fit, and what tires would I run on them if they did.

Here is the site of the wheels I want: PORSCHE WHEELS 20 INCH SILVER RIMS (POR-150-20-SLV)

You'll be hard pressed to find a knowledgeable boxster enthusiast who will give his or her approval on running 20 inch wheels, let alone a set that involves 9 inch wide fronts.

Speak for yourself Johnny, you need to open your mind... Look at this tastefully done 944...


http://members.rennlist.com/blues2/ghetto.jpg

I've been converted !

I hear ya, but this picture shows 20s and they look good. Many of the 2013s run 20s.http://986forum.com/forums/uploads01...1356619176.jpg

Bad idea
 

I wanted to share another bad wheel idea.http://986forum.com/forums/uploads01...1356619837.jpg

Just because some Euro tuner shows them on a vehicle (which by the way is a 987) doesn't mean that it's a good application. Also, any of the newer Porsche vehicles that come equipped with 20 inch wheels, involve a suspension system and geometry that's been designed to accommodate them. Putting 20 inch wheels on a 986 boxster would be a disaster from both a performance, as well as a ride quality point of view. Lastly, those Techart wheels in the photo have the weight equivalent of a dump truck !