512BBi: Tire Sizes for 17" Wheels

I have wanted to change from the Michelin TRX tires that came on my 1984 512BBi to some modern rubber with modern construction but I didn't want to deviate too much from the period correct look of the car.

The standard 512BBi metric wheels use a 240/55R415 tire on all four corners while the 512BB uses 215/70 15 on the front and 225/70 15 on the back. I do think the right bias is to be slightly bigger in the rear.

Like many others here, I bought a set of the Group 4 wheels 17" wheels for the Boxer. The fronts are 7.5" wide and the rears are 8.5" wide. I thought they were perfect for a 225 and 245 width staggered setup. The issue I found when I looked at the tires that many other people had chosen for this was that they had opted for lower profile tires than I thought was right.

Many went with 225/45 f and 245/45 or 255/45 r. The problem with this is that I thought the tires were way too low profile for the character of the car. The standard metric tries are 26.73" in overall diameter. A 225/45 17 is about 25". That's almost 2" less in overall diameter.

To make it work, I had to find some fairly unique sizes but I went with fronts of 225/55 17 which is also exactly 26.75" and very close to the original and for the rears, I went with 245/55 17 which is almost an inch bigger in overall diameter. This not only helps fill out the giant rear wheel well slightly but helps with a slight bias on a bit more rear ride height to help with better weight distribution for cornering.

Anyway, hope this might help others who are looking for help with tire sizes on their 17" wheels.

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17" image wheels with sticky kumhos
i think my rears are wider than what you mentioned.
but the daytona wheels are back on her at the moment with big balloon tires to handle Houston roads.

 

I totally agree with your choices as I also thought the low profile tire looked wrong for the car. Your tires are the most natural set up I have seen on the Group 4 wheels.

 

and the rear only 8,5" ? on my BB I have 11"

 

But don’t you have a Koenig car?

I don’t think that 11” wide would work on a standard car plus I think tire size for 17” x 11” might be a challenge.

The standard OEM wheels on the 512bbi are 415mm x 180mm front and 415mm x 210mm rear although the run a square set up in tires. The wheels end up being something like 16" x 7" front and 16" x 8.25" rear.

The 512bb stock wheels are 15” x 7.5” and 15” x 9”.

I would not have minded 9” wide in the rear but I don’t know what tire size in the rear I would have been able to go with.

I am not sure what gains you would have by going wider and/or stickier on the tires, especially considering the stress it could but on the stub axles in corners and the diff and diff carrier with acceleration. I believe this car is meant to slide a little and very wide and/or sticky tires would prevent that.

Anyway, the point of this was to show that it’s possible to have the Group 4 wheels and not go with a super low profile tire and find something that’s a bit more fitting for the car.

 

Great choices Ryan. Car looks good.
Very low profile just do not fit character of car.

 

Good day Ross,

Not just in Houston, but up here too! Although the original XWX's and 15" rims are perhaps not the best handling performance in comparison to today's tires, they are sure much more forgiving on roads that are less than optimum. In fact I am routinely surprised at how tolerant the original setup has been on our roads, rail track crossings, pot holes, and drive ramps. I have never bottomed out or jarred the car over these nasty road way issues.

Cheers,

Sam

 

Perfect fit. Well done, Ryan.

 

Those look right and period correct. I have also been concerned with the low profile look with these wheels. What Michelin tires are those? Thanks for sharing!

 

They're the Primacy 3 tires.

 

So I just ordered the Group 4 wheels and was looking at tire options. I see your setup and agree re: higher profile tires. But I'm wondering if such a rake increase is really that much better then just a smaller positive rake. I'm looking at 225/55-17 and 255/50-17 which still gives a positive rake but not to the extent of your setup. with the 255/55-17's there is also a 5% discrepancy in speed and mileage (if that matters to anyone). I found Hankook Ventus V2 Concept 2 Performance Tire. Not sure what else could be available, but I'm leaning towards this setup over the higher rake setup. Thoughts?

 

I have had Hankooks. Never ever again. Especially if the other choice was Michelin. One of the worst or the best. Not much to decide on there.

 

The thread many of you missed before you had Boxers:
The Latest BB/BBi Rim & Rubber Debate Thread
Things have obviously advanced since then, but good knowledge to had.

 

Agree that it would seem better to moderate the rake as other than increased ground clearance, there is not any benefit from doing this. Higher rake will raise the CG height and with it all the attendant disadvantages that come with that.

Having said that, the meaty looking rear tires in the OP look great.

 

Regarding rake, it’s pretty minimal. We are talking less than 0.5” difference. But if it bothers you, you can try to see if you can find 235/55 for the rear or go 225/55 on all four corners.

I love my set up, though.

Here are some more pics.

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In my opinion, this is the best looking tire setup that I have seen on the Group 4 wheels for the Boxer.

 

Just to make sure there is no confusion, I went with 245/55 in the rear, not the 255/55 to which you’re referring. It is less than an inch difference in overall diameter which means the rake would be less than half an inch.

 

Ah yes, thank you for the clarification. It's still quite an aggressive rake at 3.4% but I assume better tire options are available. However, I don't see the Primacy 3 tire available anymore in that size... When/Where did you buy them? Thank you!

 

I bought them about 5 weeks ago or so from a Michelin distributor for race tires but he said that just about any Michelin dealer should be able to get them.. The date stamps are pretty new. I’m sure they’re not out of production.

 

You are so right. I went to the Canadian site (since I'm in Montreal) and the product availability is dismal. Anyhow, I've elected a different route after much contemplation. I'll be going with a 225/50-17 and 255/45-17 setup. It's only 1" less diameter with a +0.4% rear height difference, so keeping a slight positive rake. I was also looking at 225/55-17 and 245/50-17 which would be pretty much a match to OEM diameter but with a -0.4% rear height difference, inducing a negative rake which was an impasse to me. I would choose your setup before that one. Anyhow, I'll try it out and see how it drives and if the lower profile tires don't give me eyesores. If I don't like it I'll most likely go your route.Thanks for the initial insightful post!

 

Did you settle on a size and find the tire? I just tried Tire Rack and they didn't have the 245/55 17 recommended in the string.

 

Call discount tire. They will get it for you.

 

Thanks, can you tell me what you're running and how you like them?

 

Why?

It just wont drive as nicely on the road.

The 15" earlier wheels with those big tall rounded side walls of the XWX have so much ability to abvsorb the shocks of the road. the ride on 17" will be bad after that.

the 415mm TRX wheels may well be a little taller, and have a bit less side wall and less of the roundedness, but those XWX were amazing tyres for how much shock absorption they offered. I would suggest modern tyres can still not give as nice ride for the heighth of side wall.

That TRX is pretty distintive.

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Do you get too much oversteer on the TRX?

Ferrari didn t just guess they tested these tyres, and the balance will be dealt with in the tyre pressure recomendations and the camber and caster settings will be subtly different from the XWX cars to the TRX cars.

Those rear wheel arches look a bit empty.

I would recomend sticking with what Ferrari set your car up to fit. All that expensive testing they did helped them fine tune their set up. They know best.

https://www.longstonetyres.co.uk/classic-car-tyres/ferrari/512bb.html

 

Honestly, I'd get modern tires. For my Testarossa I was able to get new 16 inch tires so I kept the same tire size, but I bought newer tire tech compared to what was available in the 80s. Safety is a big point and tires are the number 1 safety item.

So if you want to drive your car then get the best tires you can get. If you want to get 100 points at a concourse, then get the original tires.

But I could be wrong and maybe the original tires are fantastic.

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