818 Recommended Tire size for the front

[ehansen007]

I've seen all the comments going back and forth so I put a call into FFR this morning. As of today the recommended max tire size for the front is going to be 215/40/17, not 215/45/17. The right 215/45/17 will fit but I think it's more important to recognize the overall tire diameter as tires can be different. On average a 215/45/17 tire is 24.4 and that would clear however if you stay with a tire that is 24" in overall diameter with the appropriate offset, you'll have plenty of clearance. Anything larger than that and you could be rubbing. They will be correcting this in the manual. If this causes an issue, I'd wait to see what fixes may come out to take care of this instead of laying out all the frustration here in the forums. From experience I can say that as builders, we almost always find a way to figure this stuff out so stay positive and it will get it figured out.

[Frank818]

That's good to know.

Maybe FFR should also put the max sizes in terms of diameters, section width and offset? Since same tire sizes may not necessarily fit properly, changing the nomenclature or adding this nomenclature may help as a guideline.

[wallace18]

I changed out my 225/40R18 to the 215/35R18 Jim recommended. I have 1/4" clearance at the frame at full lock and 4.5" ride height.

[C.Plavan]

I changed out my 225/40R18 to the 215/35R18 Jim recommended. I have 1/4" clearance at the frame at full lock and 4.5" ride height.

What was the total diameter of the new tire that fits?

[wallace18]

What was the total diameter of the new tire that fits?

24" diameter.

[C.Plavan]

Thanks. Man- this is going to be a trial and error headache for race tires. (Possibly expensive too)

[EricScottZehnder]

I've seen several people say they're going with 235 or even 245mm fronts. Wayne is often referenced for his work on his own 818 and the GRM 818 and he's going 235mm Fronts, 265mm Rears which seems to be the best option. Thoughts?

[ehansen007]

Yes, but width is not the factor here. Its the overall tire diameter. You could run 235 or 245 in a 35 series on 18 wheels or go with a smaller 17 inch wheel. I think the most popular misconception on the sidewall rating is that it's consistent to the height of the sidewall but is is not; it is an aspect ratio and = percentage of the overall tire width. So a 215/40/18 is shorter on the sidewall than a 235/40/18 because it's 40% of 215mm vs 40% of 235mm.

But, If you're overall tire diameter is larger than 24" you will most likely rub the frame. If it were sheet metal or something you could modify easily it would be a different story but you don't want to modify the frame. When you're purchasing tires, use Tire rack's search function and then look under specs for that tire. I will give you all the dimensions you will need and give you all the alternate tire sizes in that model as well. Here's a handy little tool for measuring offset, diameter, etc.

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http://www.rimsntires.com/specs.jsp

[Ravendas]

So basically you're saying that stock tires and rims will not work, as both stock '02-'05 rims/tires and stock '06-'08 rims/tires are around 25" diameter. Good to know...

[Xusia]

So basically you're saying that stock tires and rims will not work, as both stock '02-'05 rims/tires and stock '06-'08 rims/tires are around 25" diameter. Good to know...

Actually they will work. The stock wheels are much narrower, so even though the stock tires have a larger diameter, they will clear the frame because of their narrower width.

[Frank818]

My post is now irrelevant. How interesting. I am rephrasing everything into the following:

In other words, the narrower width offsets the bigger wheel offset. Cuz the bigger the wheel offset, the more on the inside the tire will fit.

[Xusia]

I thought OEM offset was 53...

[Bob_n_Cincy]

...And also cuz of the offset which may well be more than what many people will have. OEM is 48 or 55? Many will run 35-40 up front. That brings the tire towards the inside and increases the risk of rubbing.

A smaller offset number moves the tire out.
in 2006 2.5i and outback 16" wheel with offset is 55
in 2006 wrx and sti 17" wheel 53 offset

[Frank818]

Correct I mistyped. I will edit my post the other way around.

[Wayne Presley]

stock wheels and tire fit on the GRM car without rubbing.

[Ravendas]

OEM sizes:
http://www.fastwrx.com/wrxwheelinfo.html

[Silvertop]

stock wheels and tire fit on the GRM car without rubbing.

Maybe -- though anyone (like me) planning on using the stock wheels and approximate stock tire sizing will probably want to drop down from the stock 205/55-16 to 205/50-16 in order to get the appropriate stance/rake that you will get from a 24" diameter tire rather the stock 25" one. 225/50-16 completes the setup on the rear.

[ehansen007]

Have we seen an 818 with stock tires and wheels? Me thinks we'll see a lot of fender overhang without spacers giving that "kit car" look. If spacers are used it could put one back in the same boat. I hope that's not the case but it's a big reason we all by aftermarket wheels. Only pics will tell.

[Wayne Presley]

Have we seen an 818 with stock tires and wheels?

I have

[Silvertop]

Have we seen an 818 with stock tires and wheels? Me thinks we'll see a lot of fender overhang without spacers giving that "kit car" look. If spacers are used it could put one back in the same boat. I hope that's not the case but it's a big reason we all by aftermarket wheels. Only pics will tell.

Based on the assumptions that the definitive factors are wheel offset and tire width (and that wheel width is actually irrelevant), I kind of expect that without wheel spacers, my 818 running 205/50-16s (with 53mm offset) will have the edge of the tire about 25mm (about an inch) further inboard than the guy running 215/40-17s (with 40mm offset). I computed that number by adding the difference in offset to the difference in tire width of the respective tires. I don't know if an inch is enough to make the tires look wrong in the wheel wells or not. I guess I'll find out. If it doesn't look right -- I'll get the necessary spacers.

The bigger problem may be at the rear (for properly filling the wheel wells, that is). By the same math, my 225/50-16 is likely to be about 40 mm ( just over 1 1/2") further inboard than the guy running 255/40-17s with 40mm offsets. That much is likely to be noticeable. Spacers, for sure. Assuming I have the math right, that is. Makes my head hurt.

[Bob_n_Cincy]

Based on the assumptions that the definitive factors are wheel offset and tire width (and that wheel width is actually irrelevant), I kind of expect that without wheel spacers, my 818 running 205/50-16s (with 53mm offset) will have the edge of the tire about 25mm (about an inch) further inboard than the guy running 215/40-17s (with 40mm offset). I computed that number by adding the difference in offset to the difference in tire width of the respective tires. I don't know if an inch is enough to make the tires look wrong in the wheel wells or not. I guess I'll find out. If it doesn't look right -- I'll get the necessary spacers.

The bigger problem may be at the rear (for properly filling the wheel wells, that is). By the same math, my 225/50-16 is likely to be about 40 mm ( just over 1 1/2") further inboard than the guy running 255/40-17s with 40mm offsets. That much is likely to be noticeable. Spacers, for sure. Assuming I have the math right, that is. Makes my head hurt.

Hi Silvertop
You are correct about the offset. Your 53mm -40,mm means your wheel will be 13mm inset. The 215 - 205 is 10mm but only 1/2 of this is on the outside of the tire and the other 1/2 is on the inside. So your inset is 13 + 5 =18mm , a little less than 3/4"
In the rear 225 53 to 255 40 would be a difference of 28 inset. just over an inch.
Not as bad as you thought, but still noticeable.
Bob

[Wayne Presley]

Have we seen an 818 with stock tires and wheels? Only pics will tell.

[Silvertop]

Area of interest is a little dark to tell for sure -- but it looks OK to me. Maybe I won't need to invest in spacers. Or were there spacers used in this application? Thanks, Wayne!

[Silvertop]

Hi Silvertop
You are correct about the offset. Your 53mm -40,mm means your wheel will be 13mm inset. The 215 - 205 is 10mm but only 1/2 of this is on the outside of the tire and the other 1/2 is on the inside. So your inset is 13 + 5 =18mm , a little less than 3/4"
In the rear 225 53 to 255 40 would be a difference of 28 inset. just over an inch.
Not as bad as you thought, but still noticeable.
Bob

Thanks for that correction, Bob. You are right, of course. Not as bad as I thought. Maybe no spacers will be needed. We shall see. Either way, the issue is easily resolvable.

[Wayne Presley]

With stock wheels/tires I'd use 1/2" spacers in the rears and 3/8" in the front probably based on what it looked like.

[ehansen007]

Not bad at all. The back could use some spacers but the front doesn't look bad. I'm glad the stock wheel setup works on the front. That would have been really bad.

[Silvertop]

With stock wheels/tires I'd use 1/2" spacers in the rears and 3/8" in the front probably based on what it looked like.

Sounds good to me.............