This Week on "Will It Fit"

Posted on 24 Jun 15:03
This week on "Will It Fit", we wanted to find out if a 215/65-15 BFG all-terrain tire would fit on a Quattro. Why? Because a customer wanted to know. Why? Because he put big-arse brakes on his quattro but now wants to go play in the dirt! We thought we could help especially as we had the exact same tire on our Allroad. Unfortunately we didn’t have any 16” wheels we could mount it on but we improvised.

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We were very curious because, you may remember, we had trouble fitting 275/40-17 Hosiers on the rear of ours. Not because of the width but because of the diameter which was only 25.7”. It seems the rear arches are very small so unless the chosen tire stays inside them they will impinge on the lip when travelling upwards. The BFG is 27”OD!

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We’ve also seen that 205/65-15 rally tires (25”) will rub the underside of the spring perches but, fortunately, this customer’s car is already on coilovers.

So, by balancing a tire on the jack we were able to determine that the BFG tire would just fit inside the arch lip and go up inside the wheel house, if the offset were selected appropriately. ~ET22

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Then we remembered that our coffee table consists of four 225/55-17 (26.7”) tires on ET35 Allroad wheels and a glass top so we threw one of those on and it fit.

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Then we tried it on the front:

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Unfortunately this proved even tighter than the rear, for a couple of reasons. Firstly, it rubbed on the tie rod ball joint.

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and front and rear inner fenders at full lock and full compression. Rears first.

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The ball joint is not a problem as this tire is 10mm wider than the AT tires being considered but it is also 8mm smaller diameter which means clearing the inner fenders is going to be impossible without hitting them with a BFH!

So what will fit? Turns out about 26.6” based on our jiggery-pokery.

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Yes, that’s a 25” 195/65-15 tire with a socket being used as a feeler gauge! Not very big but do bear in mind the OE tires were only 23.5” OD. Still, all is not lost. Yokohama make their excellent Geolander A/T G015 in 215/60-16 and it is “only” 26.1” OD. So this tire might be an option.

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Still hopeful we could squeeze in the 215/65-16 we got creative. We investigated whether lifting the car would help. It is on coilovers after all. This is the 25” tire at full droop and, as you can see the center is about level with the bottom of the wheel house; the bit that rubs. So, unless you lift the car to the point that this is at full compression instead we don’t think a 27” tire will work.

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Then we investigated if restricting the steering angle would help. With the small tire on we determined that full lock is about 28 degrees. Then, with the big tire on we found it doesn’t start to rub until about 22 degrees.

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We are not sure if giving up 6 degrees of lock is a lot or how to restrict the rack but it might be a way forward. Alas, that is for someone else to figure out. We have a rally car to finish.

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