need help - tire sizes for wide body

[wayner]

Please help me pick tire sizes for my wide body

My car has 9& 11 flairs. With the right spacing I can fill those with rims, it is the tires I need help with. (I’ve searched here and sufficiently confused myself).


Here is my criteria:

PERFORMANCE and WEAR
I am happy with something as good as a Yokohama ES100, so that leaves a lot of room for something even better.

Street driving and a couple track days a year. (I don’t want a second set of track tires if I can avoid it. Maybe later).

SIZE
245 is the minimum that I would like for the rear, although I could go bigger. Fronts would be sized appropriately.

QUESTIONS:
1. What brand/model tire would you recommend and what sizes?
2. What size rims?
3. Just as a 15 inch diameter is limiting, does going to an 11x17 limit my tire choices by being too wide a wheel?

I'm also open to temporary suggestions for rim sizes since I could get track rims in the future. I currently have 15x7 and 15x8 in the garage.

Thanks

[JeremyD]

I have 9's and 11's - a set of zuffenhaus fuchs and a set of True Design - both 17"

I run 255's and 315's with my Nitto NT05 street tires - that also see some track duty.

On the True Design (welded fuchs based on a set of 951 7's and 8's because I have 993 calipers) I have a set of Toyo RA'1's. The Toyo's are a little small for my rims at 235's and 275's - but I'll move up once I wear these out.

The RA1's


The Nitto's


BTW - the Nitto's are a great dual purpose tire - 200 tread wear.

[wayner]

Thanks Jeremy!

I appreciate the advice. I noted your comment about the RA1s being too small in that size and it has me wondering if I should ideally go for 10 or 10.5 rear rims to give me more tire options for the future?

Thoughts?

[JeremyD]

My RA 1's 235/275's were off my old car - where I had 8 and 9" rims (and regular Carrera Flares)

Now they are on 9" and 11" and "stretched" a little - But they fit - and with such a light car (~2350) they should heat up a little better.

When these are worn out - I will upsize them to 255/315's = probably the NT01's (which are the same compound as the RA1's)

BTW - Jeff Alton is a great guy to talk to about wheels and offsets - mine are on the money... http://www.pacificwesternperformance.com/

[wayner]

Thanks Jeremy

Your car looks great!

[wayner]

Jeremy, I noticed in another thread you mentioned 11" with a -8 ET.

I'm not familiar with the term ET. Does that mean that your 11 inch rim (5 gallon bucket) is 8 inches deep?
That doesn't sound right does it?

What sort of front side depth does your 9" rim have?

Thanks

P.S.
I will measure my car. Just trying to get a reference point.

[JeremyD]

Wheels are usually stamped with their offset using the German prefix "ET", meaning "Einpresstiefe" or, literally, "press depth". An example would be "ET45" for a 45mm offset. These are the dimensions of my wheel/tire

[wayner]

That is an excellent reference picture for understanding wheel dimensions.


Thanks!

If I understand correctly, from the centre line, an Et of -8 means that the mounting pad is "pressed in" from the wheel face far enough to reach the centre line o f the rim, plus another 8mm?

(Or perhaps pressed in from the back side to the centre and then brought back 8mm - center line of rim -8)?

[PcarPhil]

For my 98% street driven widebody I tend to use narrower tires than most. Narrower tires get up to temp quicker, are lighter, cheaper, etc. With proper offset wheels the narrower tires look fine. Remember - Porsche only used 245 width rear tires on 930's with 9x16 Fuchs.

I like 235 or 255 width tires up front and 255 or 275 width tires in the rear. 8 or 9" width front wheels with 10, 10.5, or 11" width rear wheels.

[Wil Ferch]

Wayner....No...you are confusing "offset" with "backspace".

Fictitious example. Say a wheel is 10" wide. If it is built such that the mounting surface ( say...hub assembly) is at 5" as measured from the backside.....then this wheel would have "zero" offset....and would have a "backspace" of 5".

Another wheel. This one is also 10" wide. If it is built that the mounting surface is at 6" as measured from the backside....then this wheel would have 1" of negative offset, and a "backspace" of 6".

[JeremyD]

yeah basically you take the rim width and half it -

so a 10" rim - at Zero offset would be 5" backspace and 5" rear clearance.

-8 ET would mean that it has an offset 8mm deeper from the 1/2 sectional width.

So the wider the rim (with a zero offset) makes the rim look deeper. a negative offset - with a wide rim makes it look even deeper.

The later wheels - (like from the 1989+ 964/993/996) use basically the same sizes as the earlier cars - but with offsets from +30-60mm so you find a MAJORITY of the face of the wheel looks like it's flush with the wheel rim.

@Scott - yeah I hear you - and the RA tires I have (at 235/275) are pushed out even further than the (255/315) tires that I have on my 2nd set. even at 2300-2400 lbs and a wimpy 2.7 I had no problem getting heat into them

[wayner]

Thanks Guys.

So, if we start with the centre of the rim, offset is the amount the mounting surface deviates from centre (negative farther from the back side) and that is called offset?

...and offset in German is ET?

And backspace is the resultant space left between the hub and the car side of the rim?

Did I get that right?

(I don't know why I find this so confusing but I'm sure that after a beer or two it is easier to understand )

[wayner]

I think I also just learned that if I am on a budget I should buy wheel spacers since they don't wear out as quickly as expensively wide tires. Otherwise I should just go with whatever will attract the women more, which in my case would mean hiring someone better looking to drive my car at the track

[Wil Ferch]

Wayner.....ya gottit !!

[giovanni86]

michelin tb5 rules

[wayner]

Now all I need to do is figure out what all these little thingies on the front of my welder do, and where I got this sun burn from...




This is with my 15x8 mocked up. Wider wheels are in my future I think.

[wayner]

Ok, I've been driving myself crazy with this decision. These questions are on my mind

1. Assuming the flares are big enough, are 315s really too much or will I love the look so much I have to have them?

2. Should I be stepping down to a 10.5, rather than 11 inch wheel so that I have two tire sizes that will fit instead of just one?

3. Will 17s remain popular and available, or will those sizes be orphaned ( in which case TB5s on 15s might be better)

Assuming 315 for sure, would it make sense to squeeze it on a 10.5 instead of an 11 so that I have size options later?

[PcarPhil]

Originally Posted by wayner

Ok, I've been driving myself crazy with this decision.

A couple questions for you:

How much horsepower and torque are you planning on having?

What are the expected corner weights of the car?

Those 2 questions would also influence my decision.

Really can't go too far wrong with any of the sizes mentioned in this thread.

I don't think the 17" tire sizes we're discussing are going away any time soon. 235/40/17, 245/45/17, 255/40/17, 275/40/17, 315/35/17...

[PcarPhil]

BTW I'd love to run 245/45ZR15 and 285/40ZR15 tires on 9&11x15 Fuchs on my street car. It's a shame these street tires don't exist!

[wayner]

Answers:

Weight: I'm going to throw total weight of 2300lbs out there for starters. many things have come out of the car so probably some amount less than that.

Power: Upwards of 300hp. Maybe less by some percentage.

Any of these tires including a 245 might be enough, so the main deciding point will be cosmetic, as well as choices of tires.

Among other things, what spooked me recently is Khumo dropping some of those 17 inch sizes.

Ideally I would use a tire that is stock in some common production car application.

Right now the car is wearing 245/15 on the back. with big spacers. New wheels will be 17, although tb5s on 15" would be cool.