Tyre Size - Poss expensive week ahead!

Tyre Size - Poss expensive week ahead!

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Discussion

mk1fan

Original Poster:

10,523 posts

226 months

Sunday 13th July 2014
quotequote all
Another simple q from me. What sizes are people running at the back?

One of the items on Str8six's list of 'faults' was a worn front tyre. No problem.

One of the other 'faults was one of the rear tyres rubbing, compounded by the damper set to full soft.

Now checking my sizes today I noticed that the fronts were 225/35 and the rears 235/40. Should the tyres not be the same size & profile alround?

My choice of tyre (I'm happy with it so no need for advice on model thanks) is currently 34% off so it's a good time to buy 3 (the other front is fine and 90% tread).

Cheers.


mk1fan

Original Poster:

10,523 posts

226 months

Sunday 13th July 2014
quotequote all
Thanks guys,

I think I'll bite the bullet and get 4 matching in 225/40 with load rating of 91 as I can get them at £330ish.

Coupled with the new rear wishbones I'll get a geo set up done.

mk1fan

Original Poster:

10,523 posts

226 months

Sunday 13th July 2014
quotequote all
Proxes T1R.

mk1fan

Original Poster:

10,523 posts

226 months

Monday 14th July 2014
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The T1S is around £360 for 4.

mk1fan

Original Poster:

10,523 posts

226 months

Monday 14th July 2014
quotequote all
My Owner's Book only has the 16-inch wheels noted in it, but they are the same size tyre front and rear.

mk1fan

Original Poster:

10,523 posts

226 months

Tuesday 15th July 2014
quotequote all
Right, decision made.

I'm going for a set of four Uniroyal Rainsport 3 225/40/18 91Y.

I appreciate the comments re larger rear tyres don't see the necessity given Tamy is a 'basic' 3.6 and I'm not at the stage where I need more power nor do I drive [Tamy] that 'hard' that rear grip is an issue. If matching tyres were goos enough for the factory Sagaris then they're good enough for Tamy.

Given the other jobs that need doing - rear lower wishbones replaced and upper bushes replace; top ball joints and steering rack ball joints - this gives me the opportunity to get the car set to a good baseline.

Currently got a T1R and T1S on the rear and a T1S and Falken 454 (I think) on the front.

Tyres are £360 from mytyres.co.uk (terrible site btw).

They do have the Toyo T1S in the same size etc... for a few quid more but the wet weather rating swayed me to the Uniroyal's

There are T1R on eBay for around £330 for 4
http://www.ebay.co.uk/itm/371076960620?_trksid=p20...


mk1fan

Original Poster:

10,523 posts

226 months

Wednesday 16th July 2014
quotequote all
I'm not ignoring advice. I have read the thread. The car came from the factory with same sized tyres front and rear in 16 inch version and the Sag (which in simple terms is the same basic underpinings but wider track) in 18 inch version. Why is it different for a Tamora or T350 on 18 inch wheels? It seems to be more of an 'owner' led requirement for wider rear tyres to look right rather than a dynamic requirement.

Can anyone demonstrate a significant improvement of grip between 225 and 235 tyres and by that I mean one that a regular driver is going to notice? I appreciate that this means time away from preparation for this weekends fun and games in Germany.

smile

mk1fan

Original Poster:

10,523 posts

226 months

Thursday 17th July 2014
quotequote all
I'm beginning to suspect that TVR fitted larger rear tyres on the rear 18 inch wheels for aesthetic reasons rather than dynamic.

If the 18 inch option was ticked on the order form they didn't change anything else on the car just bolted on different wheels.

It seems pretty well accepted that the 16 inch set up produced the best handling and fastest Tamora. If it was such a dynamic necessity to have wider rubber on the back then it would be even more so with the smaller rims. The manufacturer didn't feel it necessary to do so. Go up to 18 inch wheels and all of a sudden it is. I don't understand why and it would be nice if someone could explain this change if it is a dynamic requirement.

As I understand it, the Sag's track, geo, damping, springs and tyres were all the work of the external consultant and TVR adapted the body to suit. The consultant determined that, dynamically, matching tyre size was required although at 255 they are wider. Why didn't they stick with narrower tyres up front?

It seems very odd that the cars in between the 16 inch shod T chassis and the 18 inch shod Sag 'need' different sized tyres front and back.

At the end of the day it's more my curiosity as to 'why' rather than me going 'look at my tyres aren't I great'.

We all seem to want a balanced car and the two 'best' set ups from the factory had matching front and rear tyre sizes. To me, that's more than a coincidence. However, I am not a suspension guru so am happy and willing to learn.

mk1fan

Original Poster:

10,523 posts

226 months

Thursday 17th July 2014
quotequote all
TA14 said:
I think that you have a good basic point although AIUI you have your sizes back to front in that TVR would have liked to have fitted 235/40s all round on the 18" wheels due to the rim width but there were clearance issues on the front;
I hadn't considered that the fronts may be undersized. Interesting. Thanks for actually reading my question.

I have no intention of rotating tyres or swapping them round 'mid cycle'.




mk1fan

Original Poster:

10,523 posts

226 months

Thursday 17th July 2014
quotequote all
monty quick said:
Wider / grippier rear tyres reduces this risk.
Then why wasn't it required for the 16-inch wheel shod cars which had the same suspension, geo and power?

mk1fan

Original Poster:

10,523 posts

226 months

Thursday 17th July 2014
quotequote all
I am hoping they are waiting for me at home. I'll get them fitted next week. Although, I'm in Scotland the following weekend so the next drive will be 2/3 Aug out to the Sausage Meet.

mk1fan

Original Poster:

10,523 posts

226 months

Monday 21st July 2014
quotequote all
Had the tyres fitted on Saturday.

Had been due to go to a meet on Sunday but didn't go. So, at this time, the only drive was the one back from the fitters.

Away to Scotland next weekend so it'll be the following weekend before a decent run.

Initial thoughts, seems more comfortable up front, less 'wandering' whilst going straight. A trip out to the Hot Rod Diner should be a good base comparison.

Now, just a suspension and geo check.

mk1fan

Original Poster:

10,523 posts

226 months

Saturday 2nd August 2014
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Quick update.

Been out to the Sausage Meet this morning and the car feels distinctly better. Mixture of wet, drying and dry roads.

Less wandering and noticeably improved comfort up front (lot of speed humps rpund here). Deals with pot holes / dips in the road better.

I know the geo is out and this is next on the list. Oh, and three or the four replaced tyres had less than 1000 road miles on them.