O.G. Posted April 10, 2021 Share Posted April 10, 2021 My 360R (Duratec wet sump) hardly passes the Coke Can Test for Ground clearance. I have 65mm (2.5 inch) clearance unladen. There are already a few grazes showing.I was thinking of going for 14 or 15inch wheels purely for road use and keeping the current 13s for track use. I'm reluctant to change the suspension set up only to return it for track days.As well as increasing clearance this would effectively increase the gearing so I won"t be doing a very annoying and wearing 4000rpm at 70 while having to get somewhere on the motorway for instance.I accept the handling etc will be degraded somewhat but I'm prepared to live with that. After all, it would be worth it if it prevents just one cracked sump.Has anybody got any suggestions as to what of these two sizes is best for spirited mostly dry road use, and, what might give rise to even more debate, tyre choice. Obviously a conservative profile is preferable. I'm also looking to go for same width front and back.If there is anybody out there with a set of wheels they wish to sell please message me.O.G. Link to comment Share on other sites More sharing options...
John Vine Posted April 10, 2021 Share Posted April 10, 2021 As I already have 15" wheels, and wanted to avoid playing with suspension heights, I needed a different way to protect the wet sump on my R400D. I opted for a sump guard, based on James B's design (post #34 onwards).JV Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted April 10, 2021 Share Posted April 10, 2021 My 13" track slicks have an outside diameter of 530mm and the 195/50-15 road tyres are nominally 576mm diameter, so a 23mm drop in track vs road use with the same suspension settings that are optimised to have the lower wishbone parallel with the road and track rod at normal laden ride height. Link to comment Share on other sites More sharing options...
TomB Posted April 10, 2021 Share Posted April 10, 2021 Will 15s give you the ride height you want, as although the wheel will be bigger, the tyres will be of reduced profile? Link to comment Share on other sites More sharing options...
Area Representative Piers300 Posted April 10, 2021 Area Representative Share Posted April 10, 2021 Will 195/50/15 on 15” 10 spoke Caterham wheels fit within the 13” wheel arches.My car has 15” wheels and 195/45/15 CR500 tyres and it just, by a whisker, clears the 15” carbon fibre wheel arches.I bought some 15” Caterham wheels with 195/50/15’s fitted and it fouled the wheel arches. Piers Link to comment Share on other sites More sharing options...
7 wonders of the world Posted April 10, 2021 Share Posted April 10, 2021 If your running unequal sized 13" you will need to reset the rake when you switch to 15"ALL you checking needs to be done with laden weight too - pop down to B&Q and get a few bags of sand Link to comment Share on other sites More sharing options...
ScottR400D Posted April 10, 2021 Share Posted April 10, 2021 Re the last post, yes, if the 13s are different F/R the rake will alter if you fit a set of bigger rims and tyres that aren't. I'm not sure it will ruin the handling much more than you will have done already but it's a consideration. And of course the speedo will need resetting when you change the wheels though that's not too bad a task. I think I'd prefer a slightly higher than optimum ride height on the 13s for all use if it's that big a worry. Link to comment Share on other sites More sharing options...
O.G. Posted April 13, 2021 Author Share Posted April 13, 2021 Thanks all for your comments especially Piers300. Your post prompted me to do some deeper investigation and I found I only gained 15mm at the front with 15s and Avon ZZSs. Although I haven't dismissed the idea of 15s yet I wondered if 13s (or 14s) with a less racy profile might perversely give me more height.Can anybody give me spirited road going examples of what they have fitted that goes inside the arch and gives me more than 530mm diameter. 530mm is the diameter Avon quote of a 195/55 15 so that is the thing I"m trying to beat.Subject to any options I could then be looking for a set of same size 13s.O.G. Link to comment Share on other sites More sharing options...
ScottR400D Posted April 13, 2021 Share Posted April 13, 2021 I have 215/55 and 185/55 ZZRs. I wouldn't think I'd be able to get anything significantly bigger on the front the 185s already have to be manoeuvred under the wing. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted April 17, 2021 Share Posted April 17, 2021 I run R888R 185/60/13 and 205/60/13 the front fit snuggly under the 'race' front wing stays - no clearance issues though and my front rims are 6.5J Link to comment Share on other sites More sharing options...
pgm Posted April 17, 2021 Share Posted April 17, 2021 Just a thought.Have you adjustable platforms on your present dampers? If not they can be retro fitted to Bilsteins. Then have the car adjusted to the correct height on the 13's which should save the need to change wheels and tyres?Kind regards Colin (PGM) Link to comment Share on other sites More sharing options...
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